The witnesses, laying their coats at the feet of Saul, were the men that would cast the first stones at Stephen in Acts 7. Why did they all lay their coats at Saul’s feet? The Talmud contains a very interesting account of the act of stoning that may provide the answer.
“When the trial was over, they take him [the condemned person] out to be stoned. The place of stoning was at a distance from the court, as it is said, ‘Take out the one who has cursed.’[i] A man stands at the entrance of the court; in his hand is a signaling flag [Hebrew sudarin = sudar, ‘scarf, sweater’]. A horseman was stationed far away but within sight of him. If one [of the judges] says, ‘I have something [more] to say in his favor,’ he [the signaler] waves the sudarin, and the horseman runs and stops them [from stoning him]. Even if [the condemned person] himself says, ‘I have something to say in my favor,’ they bring him back, even four of five times, only provided that there is some substance to what he is saying.”[ii]
The Jewish New Testament Commentary by David H. Stern has an interesting comment about the above quote from the Talmud.
“. . .Joseph Shulam thinks sudar in later Hebrew can also mean ‘coat.’ Thus, he conjectures, the Greek translator of Acts from a presumed original Hebrew text didn’t understand the Jewish context and therefore wrote of laying coats at Sha’ul’s feet, whereas actually Shu’ul was a member of the Sanhedrin, specifically, the one who held the sudar.”[iii]
[i] Leviticus 24:14
[ii] Sanhedrin 42b