There is disagreement as to when exactly is Laylah al-Qadr.
Those who say that it is the 27th night of Ramadan cite the statement of `Ubayy b. Ka`b: “I swear by Allah that I know which night it is. It is the night Allah’s Messenger (peace be upon him) ordered us to observe standing in prayer. It is the night on the eve of the 27th of Ramadan. Its sign is that the Sun will rise in the morning of that day white without exuding any rays.” [Sahîh Muslim(762)]
However, this is the statement of a Companion exercising his judgment (ijtihâd) which he based on the indications that he mentioned.
The majority of the scholars are of the opinion that this night is not specifically known, but that it is one of the last ten nights of Ramadan. We favor the opinion adopted by Ibn Hajr that it is in one of the odd nights of the last ten days of Ramadan.
The Prophet (peace be upon him) said: “Seek it in the last ten nights, in the odd nights.” [Sahîh al-Bukhârî (2016) andSahîh Muslim (1167)]
It is a possibility that Laylah al-Qadr may actually change from year to year. It may fall on the 21st, 23rd, 25th, 27th or 29th night of Ramadan. And allah knows best.
A person should spend these nights in prayer, supplication, recitation of the Qur’ân, and the remembrance of Allah. There is no specific worship prescribed for this night, except for the supplication mentioned in the following hadîth:
`A’ishah asked: “O Messenger of Allah! If I find Laylah al-Qadr, what do you see that I should say in supplication?”
He replied: “Say: ‘O Allah! Indeed, You are the Pardoner; you love to pardon, so pardon me.” (Allâhumma! Innaka `afuww; tuhibbul-`afwa fa`fu `annî)[Sunan al-Tirmidhî(3513) and Sunan Ibn Mâjah (3850). Al-Tirmidhî declared it “a good and authentic hadîth”. Al-Albânî also authenticated it.]
We are held accountable for the nights pursuant to how we fast in our own localities.
And Allah knows best.
And Allah is most generous and merciful to His servants.