Musannaf Ibn Abi Shayba 9:697

Abu Bakr narrated to us, from Ibn Fudayl, from Yahya ibn Sa'id, from Sa'id ibn al-Musayyib, that Abu Bakr and Umar used to dislike *al-'azl* (coitus interruptus) and would command the people to perform *ghusl* (ritual washing) because of it.