Musannaf Ibn Abi Shayba 9:688

'Abdah narrated to us, from Yahya ibn Sa'id, from Sa'id, who was asked about *al-'azl* (coitus interruptus), and he did not see any harm in it. And he said: "It is your tillage; if you wish, you may leave it thirsty, and if you wish, you may water it."