Ibn Majah

Benefits and Issues:
➊
For a husband to spend the night with his wife according to the turn (bari) is the right of the woman; therefore, she can also forgo her right and give it to someone else.

➋
Leaving one's turn does not mean that all the rights of the woman are forfeited.
In such a case, the man should pay special attention to fulfilling the other rights.

➌
It was not obligatory upon the Messenger of Allah (sallallahu alayhi wa sallam) to stay with his wives according to the turn (bari).
Allah the Exalted said:

“Of them, you may put off whom you please, and you may take to yourself whom you please; and if you desire any whom you have set aside, there is no blame on you.” ( , al-Ahzab: 51)
Despite this, the Prophet (sallallahu alayhi wa sallam) would observe the turns.
This is the perfection of your (sallallahu alayhi wa sallam) noble character.

Hadith Commentary:
Lady Sawdah radi Allahu anha did this in her old age so that the Messenger sallallahu alayhi wa sallam would not divorce her.

Hadith Commentary:
(1)
In one narration, it is clarified that when Sawda bint Zam‘a radi Allahu anha became advanced in age and feared that the Messenger of Allah sallallahu alayhi wa sallam might separate from her, she said:
O Messenger of Allah! I give my turn to Aisha radi Allahu anha.
The Messenger of Allah sallallahu alayhi wa sallam accepted her request.
(Sunan Abi Dawud, Kitab al-Nikah, Hadith: 2135)
(2)
When someone gifts her turn to a co-wife, then she will receive the same day as her own turn.
If it is consecutive, then she will have two days in a row; otherwise, there will be a gap between those days.
If the remaining wives agree to the subsequent days, then she may also receive two days together.
(Fath al-Bari: 9/388)

Takhrij:
«أخرجه البخاري، النكاح، باب المرأة تهب يومها من زوجها لضرتها....، حديث:5212، ومسلم، الرضاع، باب جواز هبتها نوبتها لضرتها، حديث:1463.»©Explanation:
From this hadith, it is understood that a wife may give up her turn to another wife.
This concession will be irrevocable and non-returnable, provided that the specific days have not been designated.