564 – ʿAisha (may Allah be pleased with her) narrated that the Prophet ﷺ said, “Whoever dies while a fast is still due from him, his wali (closest relative) must fast on his behalf.” Agreed upon. (1)

Glossary of terms:
– wali: from the verb waliya (“to assume charge”). The noun wali (pattern faʿīl) means “one who takes responsibility.” Its plural is awliya, and it may refer to a relative or a supporter, male or female. As the discussion below indicates, what is meant here is the heir.

Points derived from the hadith:

1. All debts of the deceased must be settled, whether they are owed to Allah—such as zakah and fasting—or to fellow human beings.
2. The person with the strongest claim to discharge those debts is the heir, for this represents one of the greatest forms of dutifulness and kindness toward the deceased.
3. The outward sense of the hadith makes it obligatory to make up the deceased’s fasts, whether the fast was originally required by the Sharia itself or became obligatory through a vow. The indefinite noun “fast” therefore covers every type of fasting.
4. The one who carries out the fasting on behalf of the deceased is his heir, who has benefited from the estate he left. This entails settling the debts owed to Allah or to His servants, in keeping with the juristic maxims, “He who reaps the profit bears the liability,” and “Liability accompanies benefit.”
5. If the deceased leaves several heirs, they may divide the required days of fasting among themselves, each fasting a portion—whether the heirs are men, women, or both—even if they all fast on the same day.