Must the expiation for an oath (kaffarat al-yameen), which involves feeding ten needy persons, be paid immediately, knowing that the only money he has available is a debt owed to him by his brother and he will need it at the beginning of winter, or is it permissible for him to fast six days as an alternative?

The expiation for an oath is to feed ten poor persons, or to clothe them, or to free a slave. If one cannot find any of these, then he fasts for three days.

It is a condition for resorting to fasting that the person does not possess an amount exceeding his and his family's sustenance for that day and night, which would suffice for expiation. Essential needs, such as housing and similar items, fall under the ruling of sustenance.

If a person has absent money or a debt that he hopes to recover, the majority of scholars believe that he is not permitted to expiate by fasting. Instead, he should delay the expiation until he recovers the money and then expiates by feeding or clothing.