Sahih Bukhari
Wedlock, Marriage (Nikaah)
Volume: 007 / Book Number: 062 / Hadith Number: 140
Narrated Anas:
The tradition, (of the Prophet) is that if someone marries a virgin and he has already a matron wife (with him), then he should stay with the virgin for seven days; and if someone marries a matron (and he has already a virgin wife with him) then he should stay with her for three days.