Hadithcore
Sahih Muslim, 1170
sahih

Abu Huraira (Allah be pleased with him) reported:

We were talking about Lailat-ul-Qadr in the presence of the Messenger of Allah (ﷺ) and he said: He who amongst you remembers (the night) when the moon arose and it was like a piece of plate (at the fag end of the month in a state of waning).

وَحَدَّثَنَا مُحَمَّدُ بْنُ عَبَّادٍ، وَابْنُ أَبِي عُمَرَ، قَالاَ حَدَّثَنَا مَرْوَانُ، - وَهُوَ الْفَزَارِيُّ - عَنْ يَزِيدَ، - وَهُوَ ابْنُ كَيْسَانَ - عَنْ أَبِي حَازِمٍ، عَنْ أَبِي هُرَيْرَةَ، - رضى الله عنه - قَالَ تَذَاكَرْنَا لَيْلَةَ الْقَدْرِ عِنْدَ رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏

‏ أَيُّكُمْ يَذْكُرُ حِينَ طَلَعَ الْقَمَرُ وَهُوَ مِثْلُ شِقِّ جَفْنَةٍ ‏

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References2 variants
In-Book Reference
Book 13, Hadith 285
USC-MSA web (English) reference
Book 6, Hadith 2635 (deprecated numbering scheme)
Sharh · explanationclick to expand
Laylat al-Qadr is a great night. Allah points out its status in Surat al-Qadr. The Qur’an was revealed therein. Worship in it is better than worship in a thousand months. The angels descend in it with the permission of Allah, and it contains safety, security, and peace. It is known to occur, but its time is unknown. Several versions are reported from the Prophet (may Allah's peace and blessings be upon him) regarding the specification of Laylat al-Qadr or the nature of its night. This Hadīth is one of those versions, and it identifies one of the characteristics of Laylat al-Qadr. Abu Hurayrah (may Allah be pleased with him) relates that they talked to one another about Laylat al-Qadr and its status and significance, the merit of performing Qiyām al-Layl therein, and its signs which were mentioned by the Messenger of Allah (may Allah's peace and blessings be upon him). Thereupon, the Prophet (may Allah's peace and blessings be upon him) said: "Who amongst you remembers when the moon rose, and it was like a half of plate?" He likened the moon to half of a food plate. The meaning: Who amongst you remembers the night in which half of the moon appeared like half of a food plate? This was the sign of Laylat al-Qadr in this month known to them and in that year, or the sign of Laylat al-Qadr in all years. This indicates that Laylat al-Qadr can be seen and verified by whomever Allah wills..