Musannaf Ibn Abi Shayba 1:1375

Waki’ narrated to us, from Sufyan, from Muzahim, who said: I said to al-Sha’bi, "Is a vessel of an old woman that is covered more beloved to you for me to perform ablution from, or the purification vessel (mat-hara) into which the butcher puts his hand?" He said, "From the purification vessel into which the butcher puts his hand."