Sahih Muslim
The Book of Menstruation (Kitab Al-Haid)
Book Number: 003 / Hadith Number: 619
'Urwa has narrated it on the authority of 'A'isha that when Allah's Messenger (may peace be upon him) took a bath because of sexual intercourse, he first washed his hands before dipping one of them into the basin, and then performed ablu- tion as is done for prayer.