Abû Hurayra radiyallahu `anhu relates that the Holy Prophet sallallahu `alayhi wa sallam said:
"Whosoever worshipped on Laylatul-Qadr, with faith and with a sincere intention, all of his previous sins are forgiven." (from al-Bukhârî and Muslim)
From the nights of the blessed month of Ramadan, one is known as Laylatul-Qadr and during it, blessings, rewards and an abundance of good can be gained.
Allah Most high has made worship during this night worth than a thousand months, i.e. anyone who spent this night in worship, would have worshipped an equivalent of eighty three years and four months - khayru(n)m-minalfi shahr
"The night of al-Qadr is better than a thousand months." The reality is that Allah can increase the rewards gained during this month to as much as He wants and this is an amount which is beyond our imagination.
The meaning of Laylatul-Qadr in detail.
1. Imâm Zuhrî rahmatullâhi `alayh states that Qadr means status. So in comparison to other nights, this night has a greater status and hence it is known as Laylatul-Qadr (the night of power).
2 Hadrat `Abdullâh ibn `Abbâs radiyallahu `anhu relates that in this night, Allah orders the angels to write down all that has been predestined for a whole year and hence it is known as Laylatul-Qadr.
3. The following reason has also been given for it being called, "qadr":
"During this night, Allah Almighty sent His book of Power, the Holy Qur'ân to the community (ummah) of power, through the Messenger of power via which He revealed His cognition. It is for this reason that the word Qadr appears three times in this Sûrah (al-Qadr)." (Imâm Fakhrud-dîn ar-Râzî, Tafsîr al-Kabîr, 28/32)
Qadr can also mean crowded. The reason for this is that the Angels come to the earth with such excellence and goodness, that the ground becomes crowded. (al-Imâm `Alâud-dîn `Alî bin Muhammad al-Khâzin, Tafsîr al-Khâzin, 4:395)
al-Imâm Abû Bakr al-Warrâq rahî mahullâh upon commenting on Qadr, says that on this night, the worshippers are made into owners of power, even if they weren't worthy of such a thing before. (al-Imâm al-Qurtubî, Tafsîr al-Qurtubî, 20:131)
What is the reason for having this night?
The means of the Ummah gaining this blessed night is the worry the Holy Prophet sallallahu `alayhi wa sallam had aboutus. The following is stated in the Muatta of al-Imâm Mâlik rahî mahullâh:
"Allah's Messenger sallallahu `alayhi wa sallam looked back at the previous communities and saw that his community lived for a much shorter period in comparison to them. He was concerned about how his community would be able to gain as many rewards as those of the previous communities.
So when Allah the Exalted saw the concerns in the heart of His Beloved sallallahu `alayhi wa sallam. Then he sallallahu `alayhi wa sallam was given Laylatul-Qadr, which is more virtuous than a thousand months." (Imâm Mâlik, Muatta)
It is similarly narrated from Ibn `Abbâs radiyallahu `anhu, that the Holy Prophet sallallahu `alayhi wa sallam mentioned before his Companions about a man of the previous communities, who had done jihâd in the way of Allah for a thousand months:
"Then Allah's Messenger sallallahu `alayhi wa sallam became wary about his community and in this concern, made the following invocation: O my Lord, as a result of the low life span of my community, their deeds will also be low. Upon this, Allah gave Laylatul-Qadr." (al-Imâm `Alâud-dîn `Alî bin Muhammad al-Khâzin, Tafsîr al-Khâzin, 4:39)
One narration has it that the Holy Prophet sallallahu `alayhi wa sallam mentioned before his Companions, the virtues of great personalities, such as Ayyûb, Zakariyya, Hazqîl and Yûshi` `alayhimus-salâm and stated that they worshiped Allah for so many years and that they never disobeyed Allah.
The Companions who were present there, developed great desire to do the same. Imam Qurtubi writes that at that moment, angel Jibrîl came and said:
"O Prophet Muhammad sallallahu `alayhi wa sallam, your community are shocked about the eighty upon eighty years of worship made by these people. Allah has given you more," and the chapter, "innâ anzal-nâhu fî laylatil-qadri" were recited. Upon this, the face of Allah's Messenger sallallahu `alayhi wa sallam, became radiant with happiness." (Imâm al-Qurtubî, Tafsîr Qurtubî, 20:130)
So it is through the Holy Prophet sallallahu `alayhi wa sallam, that this Ummah received Laylatul-Qadr which is worth not eighty years, but eighty three years and four months and even more.
A specialty solely for the Ummah of The Prophet 
Laylatul-Qadr is a blessing which has ONLY been given to the Ummah of the Holy Prophet sallallahu `alayhi wa sallam.
al-Imâm Jalâlud-dîn as-Suyûtî rahmatullâhi `alayh, relates on the authority of Anas radiyallahu `anhu, who reports that the Holy Prophet sallallahu `alayhi wa sallam said:
"This blessed night has only been gifted to my Ummah. None of the previous communities ever received such a gift." (al-Imâm Jalâlud-dîn `Abdur-Rahmân Suyûtî, Tafsîr ad-Durr al-Manthûr, 6:371)
Who were the`abid (pious worshippers) in the previous communities?
The great Mufassirîn (scholars of tafsîr [who are learned in the science of commentating on the Qur'ânic verses]) write that in the previous communities, a person was known as an `âbid after worshiping Allah for a thousand months.
However, the Holy Prophet's sallallahu `alayhi wa sallam community has received such a gift, that we are able to gain similar rewards in just a single night!
"In the previous communities, one was an `âbid if he had been worshipping Allah for a thousand months. The Ummah of Muhammad sallallahu `alayhi wa sallam has been given this blessed night, during which every act of worship is worth more than doing that act for a thousand months." (Shawkânî, Fathul-Qadîr, 5:472)
The time for seeking repentance
This is also a great gift which has been given to those who serve the leader of the two worlds sallallahu `alayhi wa sallam.
Hadrat Sayyidinâ Anas radiyallahu `anhu relates, that the Holy Allah's Messenger sallallahu `alayhi wa sallam said at the beginning of one Ramadan:
"This month which we have entered, contains one night which is more beneficial than a thousand months. Any person who abstained from this night has rejected the good receivable during it and any person who rejected the good receivable during it is undoubtedly a rejected person." (Sunan Ibn Mâja)
What can be said about a person, who during this night avoids grasping the gifts available and chooses the path of sinning? We are prepared to stay awake for meaningless talk and socializing, but will not stay awake during a night, which contains more rewards than worship made for eighty years.
Hadrat Anas radiyallahu `anhu reports that the Holy Prophet sallallahu `alayhi wa sallam stated the following about the virtues of Laylatul-Qadr:
"During Laylatul-Qadr, Jibrâ'îl `alayhis-salam descends to the earth with some Angels and invokes Allah for the forgiveness of those who spend their time remembering Allah in any way"
This has been mentioned in Sûrat al-Qadr, in the following words:
"Therein descend the Angels and Jibrîl by Allah's permission with all decree."
Why has the time of Laylatul-Qadr been kept hidden?
The following reasons have been given for the time of Laylatul-Qadr being kept unknown:
1 Many special things have been kept hidden, for example, the Great Name (ism a`zam) and the time when every invocation is accepted during Jum`a. Similarly the timing of Laylatul-Qadr has also been kept a secret.
2 If the exact time of the night had been stated, people would neglect other nights and would only worship during this one.
3 If the exact time of the night had been stated and someone were to miss it, they may not live long enough to gain such a blessed night.
4 Allah the Exalted loves His servants to stay awake in worship during the night. So He kept the exact time of the night hidden so that in search of this night, His slaves would spend more nights in worship.
5 If the exact timing was given and a sinner commited a major offence during it, the disrespect would be considered and written down in his deeds as a transgression.
The timing of Laylatul-Qadr according to the `Ulamâ' (learned scholars)
Although the timing of this night has been ketp a secret, later scholars have given certain signs:
1. It is one of the nights of the last `ashra (ten) days of Ramadân:
Hadrat `Âisha as-Siddîqa radiyallahu `anhâ, reports that the Holy prophet sallallahu `alayhi wa sallam said:
"Seek out Laylatul-Qadr in the last ten days of Ramadân." (Sahîh al-Bukhârî)
So sitting for I`tikâf (staying in the mosque and worshipping in isolation) is also searching for Laylatul-Qadr, which is why it has been made sunnah to do this in the last ten days of Ramadân.
Before Allah Exalted revealed information about Laylatul-Qadr, the Holy Prophet sallallahu `alayhi wa sallam used to observe I`tikâf during the whole of Ramadân. However, since the revelation came about this night and till his death, he only practiced I`tikâf in the last ten days of Ramadân.
2. The twenty seventh night of Ramadân is most likely to be Laylatul-Qadr
al-Imâm al-Qurtubî rahî mahullâh writes about the opinion of the majority of the `Ulamâ' with regard to this:
"Their exists ikhtilâf (a difference of opinion) among the `Ulamâ' about the exact time of Laylatul-Qadr, but the overwhelming majority believe that it is twenty seventh night." (Imâm Qurtubî, Tafsîr al-Qurtubî, 20:134)
`Allâma Âlûsî writes:
"The preference of the `Ulamâ' is that it falls on the twenty seventh night." (Âlûsî, Tafsîr Rûh al-Ma`ânî, 3:220)
Hadrat `Abdullâh bin `Abbâs and Abî bin Ka`b radiyallahu `anhuma also hold this veiw:
Hadrat Dhû bin Jaysh radiyallahu `anhu said that he told Hadrat Abî bin Ka`b radiyallahu `anhu, that `Abdullah ibn Mas`ud stated that if a person was to worship all throughout the year, they would find Laylatul-Qadr.
Hadrat Abî bin Ka`b radiyallahu `anhu, heard and replied that he knew of `Abdullâh bin Mas`ûd radiyallahu 'anhu having knowledge of it being in the last ten nights of Ramadân and the twenty seventh night in particular.
The reason why he said this (what was related by Dhu ibn Jaysh), was so that people would not just take to worshiping during this one night, but would instead worship in every night of the year." He then stood and said, "that night is on the twenty seventh," upon which, I asked, "how do you know this?" He replied:
"Allah's Messenger sallallahu `alayhi wa sallam gave us some signs and these are only found on this night."
Sayyidinâ `Abdullâh bin `Abbâs radiyallahu 'anhu provides three evidences for the occurrence of Laylatul-Qadr falling on the twenty seventh night:
1. The word Laylatul-Qadr (in Arabic) contains nine letters and appears three times in this Sûrat [al-Qadr]. The product of this gives twenty seven. al-Imâm Fakhrud-dîn Râzî rahî mahullâh has quoted this evidence of his in the following words:
"The word Laylatul-Qadr contains nine letters and is mentioned three times in this surah, giving the product twenty seven." (Imâm Fakhrud-dîn Râzî, Tafsîr al-Kabîr, 32:30)
2. Sûrat al-Qadr contains thirty words in total and the word which gives us information about this night is "hiya", and this is the twenty seventh word of this surah:
"The Sûrat contains thirty words in total and 'hiya' is the twenty seventh word of the Sûrat." (al-Imâm Fakhrud-dîn Râzî, Tafsîr Kabîr, 32:30)
al-Imâm Abû Bakr al-Warrâq rahî mahullâh has stated this in the following words:
"Just as the month of Ramadân contains thirty days, this Sûrat contains thirty words. So every word of this surah represents a night of Ramadan. The word 'hiya' is the twenty seventh word of the Sûrat and it implies Laylatul-Qadr falling on the twenty seventh night." (al-Imâm al-Qurtubî, Tafsîr al-Qurtubî, 10:136)
3. Sayyidinâ (`Umar) Fârûq A`zam radiyallahu `anhu asked Hadrat Ibn `Abbâs radiyallahu `anhu about the timing of Laylatul-Qadr. He was given the following reply:
"Allah the Almight likes odd numbers and of these, the number seven in particular. We can see this in His creation; for example He created seven skies, seven worlds, seven days in a week, seven circuits around the Ka'ba to make one tawâf and so on." (al-Imâm Fakhrud-dîn ar-Râzî, Tafsîr al-Kabîr, 32:30)
A supplication of Laylatul-Qadr.
It is related from `Âisha as-Siddîqa radiyallahu `anhâ, that she asked the Holy Prophet sallallahu `alayhi wa sallam what she should pray during Laylatul-Qadr. He replied:
"Allahumma innaka `afuwwun tuhibbul-`afwa fa` fu `annî"
Which means:
"O Allah, you are the one who forgives and likes to forgive, so forgive me."
Taken from the Minhâj-ul-Qur'ân monthly magazine, Feb 95, pp. 8 - 12 & 20, by Shaykh-ul-Hadîth (Jâmia Islâmia Minhâj-ul-Qur'ân), Muhammad Ma`ârij-ul-Islâm: translated by Raffiq Ahmed Moosa Patel.