Is expiation for an oath (kaffarat al-yameen) due immediately, or when funds are available? And is it permissible to borrow money to fulfill it, or should one fast instead?

The scholars have differed regarding the obligation of immediately offering expiation. The preponderant opinion is that it is obligatory to offer it immediately upon ability, as the Hanbalis have stated. They cited as evidence the Hadith: "Whoever takes an oath and then sees something better than it, let him expiate for his oath and do what is better." And whoever cannot find what to feed the poor, or clothe them, or free a slave, then he must directly move on to fasting three days, due to the Almighty's saying: "But whoever finds none, then a fast of three days." If he takes a loan and pays the expiation with it, that is sufficient for him.