Musannaf Ibn Abi Shayba 13:390

Abu Usama narrated to us, from Zuhayr, who said: Ash'ath ibn Abi al-Sha'tha' narrated to me, saying: We went out, thirty riders, and over us was al-Aswad, whom Bishr ibn Marwan had appointed. He (Bishr) gave him a gift of fifty dinars, and he accepted it.