Musnad Ahmad 32:670

Husayn and ‘Affan narrated to us, they said: Khalaf ibn Khalifah narrated to us, Hafs ibn ‘Umar narrated to me, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to command marriage, and he would forbid celibacy strictly. And he would say: "Marry the affectionate, the prolific (in childbearing), for I will be boasting of your numbers against the prophets on the Day of Resurrection."