Muwatta Imam Malik Book of Marriage, Hadith 13

Yahya related to me from Malik from Ibn Shihab that Zayd ibn Thabit said, "When a man takes his wife to his house and co-habits with her then the bride-price is obliged."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، أَنَّ زَيْدَ بْنَ ثَابِتٍ، كَانَ يَقُولُ إِذَا دَخَلَ الرَّجُلُ بِامْرَأَتِهِ فَأُرْخِيَتْ عَلَيْهِمَا السُّتُورُ فَقَدْ وَجَبَ الصَّدَاقُ .