Ibn Majah 2164

[Sahih]. This hadith has corroborating narrations in Nasai, 7/310, 311, Book of Sales, chapter on the sale of a camel's excess semen (bay ghurab al-jamal), hadith no. 4677, and elsewhere. Muslim also narrated, hadith no. 1568, and elsewhere, from Rafi bin Khadij, who raised it to the Prophet, "The earnings of a cupper are impure."