Ali bin Rabi'ah narrates: I met Sayyiduna Zayd bin Arqam (may Allah be pleased with him) as he was going in to al-Mukhtar or coming out (from him). I said: A hadith has reached me from you that you heard the Messenger of Allah (peace and blessings be upon him) saying: "I am leaving among you two weighty trusts: the Book of Allah and my family ('itrah)?" He said: Yes.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5021