Abu Dawud said: Sufyan al-Thawri and Shu'bah b. al-Hajjaj reported on authority of Ubaid b. al-Hasan: There is no mention of the words "after bowing" in this tradition. Sufyan said: we met al-shaikh "Ubaid b. al-Hasan; he did not say the words "bowing" in it.
Abu dawud said: Shu'bah narrated this from Abi "Ismah, from al-A'mash, on the authority of "Ubaid, saying: "after bowing" .
In-book : Book 2, Hadith 456
English translation : Book 2, Hadith 845