Tirmidhi 108

[Sahih]. Ibn Majah also narrated it in the Book of Purification, chapter on what has been said concerning the obligation of ghusl, etc., hadith no. 608, from the hadith of Walid, with the same chain, and he stated explicitly that the narration was heard directly all the way back to Qasim bin Muhammad, and he was not alone in narrating it. Ibn Hibban graded it sahih (al-Ihsan): 1172, and it has supporting narrations.There are also narrations on this subject from Abu Hurairah [Bukhari, no. 291, and Muslim, no. 348], Abdullah bin Amr [Ibn Majah, no. 611], and Rafi bin Khadij [Ahmad, 4/143].