Bukhari

Hadith Commentary:
After this, he should stay alternately with both.
A new wife feels some estrangement from her husband, especially a virgin, for whom seven days have been prescribed so that her estrangement may be removed and her heart may become attached. After this, he should stay alternately so that it is not contrary to justice.

Hadith Commentary:
(1)
This is prescribed (masnun) because a virgin (bikr) possesses greater modesty and shyness. She is also more deserving of love, affection, and loyalty; therefore, seven days have been designated for her so that her apprehension may be removed and her heart may become attached. Furthermore, she prefers ease and gentleness from her husband. As for the previously married woman (thayyib), three days have been designated for her because she becomes familiar more quickly and blends into the environment. She has already experienced a husband, and due to intercourse, her shyness is also lessened.
(2)
It should be noted that these are the days in which there is nothing preventing intimacy, and during which the woman is not experiencing menstruation (hayd).
And Allah knows best.

Hadith Commentary:
Some individuals hold the view that the husband should stay for three days with both a previously married woman and a virgin. Their argument is that staying seven days with a virgin and three days with a previously married woman is contrary to justice and fairness. However, this stance is against the aforementioned ahadith. Furthermore, in another hadith, this matter is clarified further: When the Messenger of Allah (sallallahu alayhi wa sallam) married Umm Salamah (radi Allahu anha), he said to her:

"Your family is extremely respected by me. If you wish, I can stay with you for seven days, but in that case, I will also stay seven days with each of my other wives, and then the regular rotation will be established. And if you wish, I will stay with you for three days, and immediately after that, the regular rotation will be established."

So Umm Salamah (radi Allahu anha) said: "You may stay with me for only three days."

(Sahih Muslim, Al-Rada', Hadith: 3622 (1460))

Explanation:

1:
A Companion’s statement, “The Sunnah is this,” is also an indication that the hadith is marfu‘ (attributed to the Prophet sallallahu alayhi wa sallam). This is the view of all the Imams.

Benefits and Issues:
➊
When a new marriage is contracted while the first wife or wives are present, the husband should stay with the new bride for a few days and then establish a schedule for turns.

➋
If the new bride is a widow or divorced woman, meaning this is her second marriage, then the husband should stay with her for three days, that is, he should reside in the house or room designated for her residence. And if the new wife is a virgin (never married), then he should stay with her for a full week.

➌
Staying with the new wife for three or seven days does not mean that during this period the first wives should be completely neglected. The meaning is that he should give her more time and spend the night with her.

➍
After this period ends, the new wife will have the same rights as the previous wives. Just as the other wives have their turns, so too will the new wife have her turn. The husband will treat her in terms of expenses and overnight stays just as he does with the other wives. He will spend the night with her only when it is her turn.

Benefits and Issues:
➊ For a Companion (sahabi) to declare an action as Sunnah is evidence that it is marfu‘ (attributed to the Prophet sallallahu alayhi wa sallam).

➋ The specification of three or seven days pertains to the initial days; after that, turns should be assigned with justice and the established system should be followed accordingly.

Takhrij:
«أخرجه البخاري، النكاح، باب إذا تزوج الثيب علي البكر، حديث:5214، مسلم، الرضاع، باب قدر ما تستحقه البكر والثيب من إقامة الزوج عندها عقبالزفاف، حديث:1461.»©Explanation:
This hadith proves that spending the wedding nights with the new wife is her right, and she will be given preference over the other wives.
After this period ends, then both the new and previous wives have equal entitlement in the division of turns.