Musannaf Ibn Abi Shayba 33:1066

Affan narrated to us, he said: Hammad ibn Salamah narrated to us, he said: Ata ibn al-Sa’ib informed us that: When Abu al-Bakhtari and his companions would hear one of them being praised, or if vanity entered him, he would bend his shoulders and say: "I have humbled myself for Allah."