Sahih al-Bukhari 5214
صحيح البخاري#5214SahihNarrated Anas:It is the Prophet's tradition that if someone marries a virgin and he has already a matron wife then he should stay for seven days with her (the virgin) and then by turns; and if someone marries a matron and he has already a virgin wife then he should stay with her (the matron) for three days, and then by turns
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 67:147