Musannaf Ibn Abi Shayba 21:759

Hashim ibn al-Qasim narrated to us, he said: Abu Aqil narrated to us, he said: Mujalid narrated to us, from al-Sha'bi, from Masruq, who said: When Ibn Mas'ud would buy a slave, he would say: "O Allah, bless us in him, and make him long-lived and abundant in provision."