Is it permissible for a young man who is financially capable of feeding ten poor persons to fast three days as expiation for an oath, with the aim of saving money for his future and marriage?

Whoever swears not to commit something unlawful is obligated to fulfill his oath. If he commits it, then expiation is due upon him by consensus, which is feeding ten poor persons, or clothing them, or freeing a slave. If he cannot find any of these, then he must fast for three consecutive days. The one who is unable is he who does not find anything in excess of his and his family's sustenance for their day and night, or one who is eligible to receive zakat.