Allah's Apostle (may peace be upon him) said: I see that your dreams agree regarding the last ten (nights of Ramadan). So seek it on an odd number (of these ten nights). [Muslim :: Book 6 : Hadith 2619]

Abu saeed al khudri reported that Prophet (s) said: And he who desires to observe i'tikaf along with me should spend the night at his place of i'tikaf. And I saw this night (Lailat-ul-Qadr) but I forgot it (the exact night) ; so seek it; In the last ten nights on odd numbers. [Muslim :: Book 6 : Hadith 2625]

Narrated 'Aisha:

Allah's Apostle said, "Search for the Night of Qadr in the odd nights of the last ten days of Ramadan."
[Bukhari :: Book 3 :: Volume 32 :: Hadith 234]

Ibn Umar (Allah be pleased with them) reported Allah's Messenger (may peace be upon him) as saying: Seek it (Lailat-ul-Qadr) in the last (ten nights). If one among you shows slackness and weakness (in the earlier part of Ramadan), it should not be allowed to prevail upon him in the last week. [Muslim :: Book 6 : Hadith 2621]

Narrated Ibn 'Abbas:

Allah's Apostle said, "The Night of Qadr is in the last ten nights of the month (Ramadan), either on the first nine or in the last (remaining) seven nights (of Ramadan)." Ibn 'Abbas added, "Search for it on the twenty-fourth (i.e. on 25th night of Ramadan)." [Bukhari :: Book 3 :: Volume 32 :: Hadith 239]

Narrated 'Ubada bin As-Samit:

The Prophet came out to inform us about the Night of Qadr but two Muslims were quarreling with each other. So, the Prophet said, "I came out to inform you about the Night of Qadr but such-and-such persons were quarreling, so the news about it had been taken away; yet that might be for your own good, so search for it on the 29th, 27th and 25th (night of Ramadan).

[Bukhari :: Book 3 :: Volume 32 :: Hadith 240]

Ibn Numair reported Allah's Messenger (may peace be upon him) as saying: Look for Lailat-ul-Qadr in the last ten nights of Ramadan. [Muslim :: Book 6 : Hadith 2632]

Brothers and sisters there are hadeeths in sahih muslim that few sahabas say they are sure that it's on 27th night on ramadhan, while few sahabas state it on 25th night, and few sahabas have stated it on 23rd night,and some have stated it on 21st night.

Some of the ahadeeth indicate that Lailatul-Qadr is in the last ten nights, while others indicate that it is in the odd nights of the last ten, so the first is general and the second is more particular, and the particular has to be given priority over the general. Other ahadeeth state that it is in the last seven - and these are restricted by mention of one who is too weak or unable. So there should be no confusion.

Conclusion: The Muslim should seek out Lailatui-Qadr in the odd nights of the last ten: the night of the twenty-first, the twenty-third, the twenty-fifth, the twenty-seventh and the twenty-ninth. If he is too weak or unable to seek it out in all the odd nights, then let him seek it out in the odd nights of the of seven: the night of the twenty-fifth, the twenty-seventh and the twenty-ninth.

Brothers and sisters, as the mother of all believers, Aisha (raziALLAHu anha) have narrated that:
"With the start of the last ten days of Ramadan, the Prophet used to tighten his waist belt and used to pray all the night, and used to keep his family awake for the prayers."

The reason for being that this night is too great and majestic as ALLAH (SWT) HAS Stated it in Quran that: [097:003] " The Night of Al-Qadr (Decree) is better than a thousand months" (i.e. worshipping Allâh in that night is better than worshipping Him a thousand months, i.e. 83 years and 4 months).

Hence, we should atleast search it in odd nights of the last ten nights of Ramadhan, if we cannot search it on all the nights consecutively.

We pray to Allah All Mighty Most Merciful to bless us this Ramadan by making us witness the Laylatul-Qadr and to get all it's rewards.

Recommended Dua of This night: It is recommended to pray, read Quran with understanding and reflecting on each verses, and supplicate a lot during this night, it is reported from our mother 'Aishah radhiya Allahu `anha, that she said: "O Messenger of Allah! What if I knew which night Lailatul-Qadr was, then what should I say in it?" He (s) said.- "Say.-

(Allahumma innaka 'affuwwun tuhibbul 'afwa fa'fu 'annee.)

"O Allaah You are The One Who pardons greatly, and loves to pardon, so pardon me.". [at-Tirmithi and Ibn Majah with a Sahih Isnad]

Final Take: The Night of Al-Qadr is not specified to one fixed night throughout all the years. Rather, it constantly changes. So one year it could occur on the twenty-seventh night for example and on another year it could occur on the twenty-fifth night, according to Allah's Will and Wisdom. What directs us to this is the Prophet's :saw: saying: "Look for it (i.e. the Night of Al-Qadr) when there remain nine nights, when there remains seven nights, or when there remains five nights (i.e. 21st, 23 rd, 25th, 27th and 29th)." [This is taken from the book of Shaikh Muhammad Ibn Saalih al-'Uthaimin in his book Majaalis Shahr Ramadan (pg.106 -107). Reported by Muslim and others and it is referenced in Sahih Abu Dawud (1247)]