(There is another chain) from Yahya bin Sa'eed that Al-Qasim bin Muhammad saw them sitting in Tashah-hud, so he mentioned the Hadith.
Sunan Abi Dawud Book 2, Hadith 572
← Previous Hadith Hammad bin Zaid also said (the wording): "From the Sunnah" (narrating) from Yahya just as Jarir did.

Sunan Abi Dawud Book 2, Hadith 571 Next Hadith → "When the Prophet (ﷺ) would sit in the prayer, he would place his left foot horizontally - so much so that the upper-part of his foot became black."

Sunan Abi Dawud Book 2, Hadith 573