Sahih Muslim 762 e
Zirr b. Hubaish reported that Ubayy b. Ka'b (Allah be pleased with him) said about Lailat-ul-Qadr:
By Allah, I know well about it. Shu'ba said: To the best of my knowledge it was the twenty-seventh night for which the Messenger of Allah (ﷺ) commanded us to stand for prayer. Shu'ba doubted these words: That it was the night for which the Messenger of Allah (ﷺ) commanded us to stand for prayer. And (he further) said: This was narrated to me by a friend of mine from him (the Holy Prophet).
وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، قَالَ سَمِعْتُ عَبْدَةَ، بْنَ أَبِي لُبَابَةَ يُحَدِّثُ عَنْ زِرِّ بْنِ حُبَيْشٍ، عَنْ أُبَىِّ بْنِ كَعْبٍ، - رضى الله عنه - قَالَ قَالَ أُبَىٌّ فِي لَيْلَةِ الْقَدْرِ وَاللَّهِ إِنِّي لأَعْلَمُهَا - قَالَ شُعْبَةُ وَأَكْبَرُ عِلْمِي - هِيَ اللَّيْلَةُ الَّتِي أَمَرَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم بِقِيَامِهَا هِيَ لَيْلَةُ سَبْعٍ وَعِشْرِينَ ‏.‏ وَإِنَّمَا شَكَّ شُعْبَةُ فِي هَذَا الْحَرْفِ هِيَ اللَّيْلَةُ الَّتِي أَمَرَنَا بِهَا رَسُولُ اللَّهِ صلى الله عليه وسلم ‏.‏ قَالَ وَحَدَّثَنِي بِهَا صَاحِبٌ لِي عَنْهُ ‏.‏