What is the ruling on someone who broke an oath and is obligated to fast three days, while it is Ramadan?

If a person is obligated to offer expiation for an oath (kaffarat yameen), it is not permissible for him to fast for three days except after being unable to feed ten poor persons, or clothe them, or free a slave, according to the Almighty's saying: {Its expiation is the feeding of ten poor persons from the average of that which you feed your own families, or clothing them, or freeing a slave. But whoever finds not [the means to do so] – then a fast of three days.} And in the case where fasting is permissible, it is not valid until after the completion of Ramadan.