Musannaf Ibn Abi Shayba 1:1724

Mu'alla ibn Mansur narrated to us, he said: Al-Haytham ibn Humayd narrated to us, from Al-'Ala' ibn al-Harith, from Makhul, from 'Anbasa ibn Abi Sufyan, from Umm Habibah, she said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever touches his private part, let him perform ablution."