Musannaf Ibn Abi Shayba 9:542

Zayd ibn al-Hubab narrated to us, from al-Dahhak ibn Uthman, who said: Al-Zuhri was asked about a man who married a woman while he was capable of paying her dowry: "May he consummate the marriage with her without having given her anything?" He said: "The Sunnah has passed that he should not consummate the marriage with her until he gives her something."