Hadithcore
Sunan Abi Dawud, 1428
da’if· Al-Albani

Muhammad reported on the authority of some of his teachers that Ubayy b. Ka'b led them in prayer during Ramadan. He used to recite the supplication (in the witr) during the second half of Ramadan.

حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدِ بْنِ حَنْبَلٍ، حَدَّثَنَا مُحَمَّدُ بْنُ بَكْرٍ، أَخْبَرَنَا هِشَامٌ، عَنْ مُحَمَّدٍ، عَنْ بَعْضِ، أَصْحَابِهِ أَنَّ أُبَىَّ بْنَ كَعْبٍ، أَمَّهُمْ - يَعْنِي فِي رَمَضَانَ - وَكَانَ يَقْنُتُ فِي النِّصْفِ الآخِرِ مِنْ رَمَضَانَ ‏.‏

References2 variants
In-Book Reference
Book 8, Hadith 13
English Reference
Book 8, Hadith 1423