“The ḥamw is death”: The Prophet likened the husband’s in-law (ḥamw) to death, because his unopposed entry into the house may end in spiritual ruin. Ibn Ḥajar states in Fatḥ al-Bārī: “The Arabs often describe whatever they dislike as ‘death.’”

Overall meaning
The Prophet ﷺ warns against entering upon unrelated women and against being alone with them, for whenever a man isolates himself with a woman, Satan is their third. Human souls are weak and the impulses that lead to sin are strong; forbidden acts readily occur. Therefore he forbade seclusion with them so as to keep far from evil and its causes.

A man then asked, “O Messenger of Allah, what about the ḥamw who is a close relative of the husband? He may need to enter his kinsman’s house where the wife is present—does he have a concession?”

The Prophet ﷺ answered, “The ḥamw is death,” because people customarily take the matter lightly and feel no aversion to his entry. He may then find himself alone with a woman who is not lawful to him, and immorality could take place without anyone’s noticing or suspecting—bringing spiritual destruction and everlasting ruin. Hence there is no concession; rather, beware of him and of his moments of seclusion with your womenfolk, if you have any sense of protective jealousy.

Lessons derived from the ḥadith

1. It is forbidden to enter upon unrelated women or to be alone with them, in order to block the means that lead to adultery.
2. The ruling applies to all non-maḥram male relatives of the husband, such as his brother and cousins. Ibn Daqīq al-ʿĪd notes, however, that the prohibition holds when such entry entails seclusion; if no seclusion results, the entry is not barred.
3. The prohibition here belongs to the category of forbidding the means; the ruling on a means follows the ruling on its ends.
4. One must keep away from all situations that are prone to error, for fear of falling into sin.
5. Shaykh al-Islām Ibn Taymiyyah relates that ʿUmar ibn al-Khaṭṭāb used to order unmarried men not to live among those who were married, nor married men among bachelors, and that the Emigrants acted likewise when they arrived in Medina during the Prophet’s lifetime.