It is narrated from Sayyiduna Talq bin Ali (may Allah be pleased with him) that he said: I said: "O Messenger of Allah, what do you say about a man who performs ablution, then lowers his hand and touches his private part, or sprinkles water on it?" He (peace and blessings be upon him) said: "It is but a part of you."
Hadith Referenceالمعجم الكبير للطبراني / باب الطاء / 8202