Musannaf Ibn Abi Shayba 37:624

Ya'la ibn 'Ubayd narrated to us, from Musa al-Juhani, from Qays ibn Yazid, who said: My freedwoman, Sidra, narrated to me that my grandfather, Salama ibn Qays, narrated to me, saying: I met Abu Dharr, and he said: "O Salama ibn Qays, there are three things I have memorized: Do not bring co-wives together, for you will never be able to treat them justly even if you strive to do so. Do not work as a collector of Zakat (Sadaqah), for the one in charge of Zakat is prone to excess and deficiency. And do not deceive a person of authority, for you will not obtain anything from their worldly life without them obtaining something better than it from your religion."