Al-Hakam, or Abu al-Hakam, al-Thaqafi narrates from his father (may Allah be pleased with him) that "Whenever the Messenger of Allah (peace and blessings be upon him) performed ablution, he would sprinkle water in the direction of his private part."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3163