Is Zihar comparable to other types of oaths in terms of when the obligation takes effect?
General Chapter
Al-Mughni
Book of Zihar
Primary text
Zihar is a form of expiable oath (yamin mukaffarah), and expiation is only due upon breaking the vow (al-hanth), which is performing the act sworn against (intercourse), just like other oaths. Since it is an oath requiring abstinence from intercourse, its expiation is not due until the act it forbids is performed, analogous to Ila'.
Supporting text
The validity of Zihar against a non-wife before marriage is established because it is a binding oath, and oaths sworn to Allah are valid even before marriage. The apparent restriction in the Quran to 'their women' is understood as descriptive of the usual case, not restrictive, similar to how the mention of a stepdaughter in one verse does not restrict the ruling solely to her.