Musannaf Ibn Abi Shayba 9:1176

Waki' narrated to us, he said: Isma'il narrated to us, from Qays, from 'Abdullah, who said: We were with the Prophet (peace be upon him) while we were young men. He said: So we said, "O Messenger of Allah, shall we not castrate ourselves?" He said, "No." Then he granted us a concession to marry a woman for a garment for a specified term. Then 'Abdullah recited: "O you who have believed, do not prohibit the good things which Allah has made lawful to you."