Musannaf Ibn Abi Shayba 9:282

Abu Bakr narrated to us, he said: Mu'tamir ibn Sulayman narrated to us, from Ibn Suwayd, that Umar ibn Abd al-Aziz wrote: "When a man consummates the marriage with a woman, the immediate [dowry] becomes due, as well as the deferred [dowry], unless a condition is made regarding the deferred [dowry]."