Abu Qilābah (may Allāh have mercy on him) said:
“The Night of Decree moves (each year) during throughout the last ten nights (of Ramadhān).”
عَنْ أَبِي قِلاَبَةَ أَنَّهُ قَالَ لَيْلَةُ الْقَدْرِ تَنْتَقِلُ فِي الْعَشْرِ الأَوَاخِرِ
Jami` at-Tirmidhi 792
Ibn ‘Abdil-Barr (rahimahullaah) said:
“Indeed; a group from the people of knowledge held that Laylatul Qadr in every Ramadhaan is on the twenty first night, whilst others held that it is on the twenty third night every Ramadhaan. Yet others held that it is on the twenty seventh night every Ramadhaan, and others held that it changes position in each odd night from the last ten – and this is that which is correct with us – if Allaah wills.”
[At-Tamheed vol 23 p.63]
Ibn Kathīr (may Allah have mercy on him) commented on this statement, writing
“This view narrated from Abu Qilabah has also been recorded by Malik, Al-Thawri, Ahmad ibn Hanbal, Ishaq ibn Rahuwayh, Abu Thawr, Al-Muzani, Abu Bakr ibn Khuzaymah, and others. It has been related from Al-Shafi’i and Al-Qadi reported it from him. This is most likely the case. Allah knows best.”
Tafsīr Ibn Kathīr Surah-Al- Qadr 97
Al-Haafidh Ibn Hajr said in Fath-ul-Bari: “The most strongest opinion is that it is on an odd night in the last ten nights and that it constantly changes.”
Shaykh al-Albanee said that the night of decree moves every year (It is not limited to the twenty-seventh) in the month of Ramadan.
Listen to Sheikh Al-Albanee here.
The opinion of Ibn al-Taymiyyah is that it could be on the even nights perse. His statement in Arabic is below:
قال شيخ الإسلام ابن تيمية: “لكن الوتر يكون باعتبار الماضي فتطلب ليلة إحدى وعشرين، وليلة ثلاث وعشرين، وليلة سبع وعشرين، وليلة تسع وعشرين، ويكون باعتبار ما بقي كما قال النبي : “لتاسعة تبقى، لسابعة تبقى، لخامسة تبقى، لثالثة تبقى”. فعلى هذا إذا كان الشهر ثلاثين يكون ذلك ليالي الأشفاع، وتكون الاثنان والعشرون تاسعةً تبقى، وليلةُ أربع وعشرين سابعة تبقى. وهكذا فسره أبو سعيد الخدري في الحديث الصحيح، وهكذا أقام النبي في الشهر… وإذا كان الأمر هكذا فينبغي أن يتحراها المؤمن في العشر الأواخر جميعه”
What he mentioned was the possibility that it was on the odd nights either counting from the beginning of the month, or from what was left of it. In the narration he brings up, the Prophet ﷺ told us to seek it in the last 10 remaining nights. And we would have to calculate that from the end of the month because that is how we would be able to tell when the last 10 nights were. And how do you know the last 10 remaining nights? You don’t until you finish the month. The month could be either 29 days, meaning that you would count the last ten from the 19th, and that would be first. Or it could be 30 days, making the 20th the first odd night of the last 10 nights, counting from what remained.
And it’s actually a fascinating opinion too, because it does well to reconcile between the ahadith telling us to look for Laylatul Qadr in the last 10 nights (all of it). Because in reality, we don’t know which is odd – so we should try our hardest in all those nights, not just that we assume it to be the odd nights. Otherwise what happens, is that people don’t pay any attention to the ‘even’ nights – when in reality, it could be the odd nights of the last 10 nights in which the Prophet ﷺ told us to look for Laylatul Qadr.
والله أعلم