One makes atonement for something he has made unlawful for himself.* You have had a good example in God’s Messenger.
* i.e. something not in itself unlawful. It is treated like an oath for breaking which atonement must be made. The Prophet’s example refers to his withdrawing from his wives for a period.
‘A’isha said that God’s Messenger gave them their choice and they chose God and His Messenger; so that was not reckoned as counting in any way to their divorce.
The Prophet used to spend time with Zainab daughter of Jahsh and that he once drank honey at her house, so Hafsa and she agreed that the one whom the Prophet visited first should say, “I notice that you have an odour of the gum of the mimosa.* Have you eaten some?” When he visited one of them and she said that to him he replied, “Don’t worry; I drank some honey at the house of Zainab daughter of Jahsh, but I swear that I shall not do it again. Do not tell anyone of that.” desiring to please his wives, and then there came down, “O prophet, why do you hold to be forbidden what God has made lawful for you, desiring to please your wives? (Al-Qur’an 66:1).
*Maghafir; plural of Mughfur, is here used. It is the gum of a kind of mimosa called ‘urfut, the odour of which is unpleasant.
'Abdallah b. ‘Umar said he divorced a wife of his while she was menstruating and that when ‘Umar mentioned the matter to God’s Messenger he became angry and said, “He must take her back and keep her till she is purified, then has another period and is purified. If it then seems good to him to divorce her he may do so when she is pure from the menstrual discharge before having intercourse with her, for that is the period of waiting which God has commanded for the divorce of women.” A version has, “Command him to take her back, then divorce her when she is pure from the menstrual discharge, or pregnant.”