It is reported about Sayyiduna Abdullah bin Salam (may Allah be pleased with him) that he said: O Messenger of Allah! Before you, we were People of the Book, and we were commanded to wash the private parts (after defecation and urination). The Prophet (peace and blessings be upon him) said: Indeed, Allah Almighty is pleased with you, He has praised you, and He has expressed His love for you.
Imam al-Tabarani recorded this narration in al-Mu'jam al-Awsat; its chain contains a narrator, Sallam al-Tawil, whose weakness the hadith scholars agree upon.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1056