Sayyiduna Usamah bin Zayd bin Harithah (may Allah be pleased with them both) narrates from his father that Jibril (peace be upon him) came to the Prophet (peace and blessings be upon him) when revelation was first sent to him, and he taught him (peace and blessings be upon him) ablution. the Prophet (peace and blessings be upon him) performed ablution, and when he had finished (the ablution), the Prophet (peace and blessings be upon him) took water in his hand and sprinkled it on his private part.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 756