Sayyiduna Wathilah bin al-Asqa' (may Allah be pleased with him) says: When I became Muslim, I came to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said to me: "Go and take a bath (ghusl) with water and lote-tree leaves, and remove from yourself the hair of disbelief."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18419