Musannaf Ibn Abi Shayba 21:344

Sharik narrated to us, from al-A'mash, from Salim, who said: It was said to Abu al-Darda', "Indeed, Abu Sa'd ibn Munabbih has set free one hundred slaves from his wealth." He said, "Indeed, one hundred freed slaves from a man's wealth is a great deal. Shall I not inform you of what is better than that? Faith that is adhered to by night and by day, and that your tongue remains moist with the remembrance of Allah."