Sahih Muslim
The Book of Menstruation (Kitab Al-Haid)
Book Number: 003 / Hadith Number: 726
Ibn 'Abbas reported: We were with the Apostle of Allah (may peace be upon him) and he had come out of the privy. Food was presented to him. It was said to him (by the Companions around him): Wouldn't you perform ablution? Upon this he said: Why, am I to say prayer that I should perform ablution?