Musannaf Ibn Abi Shayba 13:2304

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Hisham al-Dastawa’i narrated to us, from Qatadah, from Sa’id ibn al-Musayyib, who said: Every calculation that you calculate, and you take a wage for it, it is of no benefit.