Wedlock, Marriage (Nikaah)

Bukhari :: Book 7 :: Volume 62 :: Hadith 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.