What is the ruling if one vows I'tikaf contingent upon the arrival of a specific person on a specific day?
General Chapter
Al-Mughni
Book of I'tikaf
Primary text
If one vows I'tikaf contingent upon the arrival of a specific person, the vow is valid if the condition is possible. If the person arrives during the day, one must observe I'tikaf for the remainder of that day, and no makeup is required for the time missed before the condition was met, as the obligation was suspended until the condition materialized. However, if fasting is a prerequisite for I'tikaf validity, one must make up a full day because one cannot perform the required I'tikaf with fasting for the remaining part of the day, nor can the missed portion be compensated separately.
Supporting text
It is possible that observing the remainder of the day suffices if one is fasting. If the person arrives at night, nothing is due because the contingent obligation did not materialize. If the vow-maker has a valid excuse preventing I'tikaf upon the person's arrival (such as imprisonment or illness), they must offer expiation for failing the vow in its time, and they must make up only the remainder of the day, according to one narration, or a full day, according to another, based on whether fasting is considered a prerequisite for I'tikaf.