Musannaf Ibn Abi Shayba 13:2305

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Hammam ibn Yahya narrated to us, from Qatadah, from Yazid al-Rishk, from al-Qasim, who said: I said to Sa’id ibn al-Musayyib: "What is your opinion regarding the earnings of a partitioner (qassam)?" He disliked it. I said: "I work in it until my forehead sweats," yet he did not grant me a concession in it. Qatadah said: And al-Hasan used to dislike his earnings. Qatadah said: And Ibn Sirin said: "If it is not foul (khabith), then I do not know what it is."