Musnad Abu Ya'la al-Mawsili 129:170

Zuhayr narrated to us, Ismail narrated to us, from Humayd, from Anas, that Abd al-Rahman ibn Awf married [a woman] for the weight of a date pit of gold. The Messenger of Allah (peace and blessings of Allah be upon him) said to him, "Give a wedding feast, even if with a sheep."