Muslim

For details, see the previous hadith.

Hadith Commentary:
(1)
Other rulings and issues related to mourning (iddah) will be discussed in the Book of Divorce (Kitab al-Talaq), but it is necessary to clarify here that if the wife was pregnant at the time of her husband's death, then the duration of her mourning (iddah) is until childbirth, whether the delivery occurs before or after four months and ten days.

In this narration, the report of Abu Sufyan’s (radi Allahu anhu) death coming from the region of Sham (Greater Syria) is based on a misconception, because his death, by consensus, occurred in Madinah Munawwarah.

The one who passed away in Sham was the dear brother of Umm Habibah (radi Allahu anha), Yazid ibn Abi Sufyan (radi Allahu anhu), as clarified in Sunan al-Darimi and Musnad Ahmad, among others.

(Fath al-Bari: 3/188) (2)
From these ahadith, it is understood that only a wife may mourn for her husband for four months and ten days; it is not permissible to mourn for any other deceased person for more than three days.

Even in the case of a wife mourning her husband for this duration, there are several Islamic benefits and wisdoms, which we will explain later.

(3)
Zaynab bint Jahsh (radi Allahu anha) had three brothers:
Abdullah, Ubaydullah, and Abu Ahmad.
Abdullah was martyred in the Battle of Uhud, at which time Zaynab had not yet married the Messenger of Allah (sallallahu alayhi wa sallam).
Ubaydullah was a Christian; he died as a Christian in Abyssinia.
The Messenger of Allah (sallallahu alayhi wa sallam) married Zaynab after his (Ubaydullah’s) death, as Zaynab was very young at the time of Ubaydullah’s passing.
Zaynab (radi Allahu anha) passed away during the lifetime of Abu Ahmad.

Thus, the question arises: for which brother’s death did Zaynab observe mourning? The answer is that the Mother of the Believers, Zaynab bint Jahsh (radi Allahu anha), had a half-brother or foster brother, and she observed mourning upon his death.

(Fath al-Bari: 3/189)

Benefits and Issues:

➊
During the waiting period (‘iddah) after a husband's death, it is necessary to abstain from wearing jewelry and other items of adornment. Clothing should also be simple.

➋
During the ‘iddah, it is not permissible to use anything for treatment that is also used for adornment, for example: applying kohl (surmah) to the eyes or henna (mehndi) to the hands. For treatment during this period, other items should be used.

➌
The waiting period (‘iddah) after death is four months and ten days. However, if the woman is pregnant, her ‘iddah lasts until the birth of the child, whether the birth occurs before the completion of four months and ten days or after that period. (Sunan Ibn Majah, Hadith 2027, 2030)

➍
The rulings of Islam are both better and easier than non-Islamic customs and traditions. Therefore, if any difficulty is felt in them, one should endure it and act only upon the Shari‘ah rulings.

➎
The act of throwing away camel dung is an allusion to the era of ignorance (Jahiliyyah). In that time, when a woman's husband died, she would reside in a hut, wear old clothes, and not use any fragrance or the like. After spending the entire year in this manner, when she would come out, she would take a piece of camel dung and throw it away. This was as if to express that a year of mourning for her deceased husband was as insignificant to her as picking up and throwing away a piece of dung. Islam abolished this evil custom. (Sahih al-Bukhari, Book of Divorce, Chapter: The waiting period of a woman whose husband has died is four months and ten days)