Musannaf Ibn Abi Shayba 1:711

711. Abda bin Sulayman narrated to us, from Ibn Abi Khalid, from Jabir bin Zayd, who said: Jabir was asked about the washing for major ritual impurity (janaba). He said: "A sa'." He said: "I do not think it is sufficient for me." Jabir said: "Yes, it is."