Is expiation required of one who swore not to commit a sin but then committed it, knowing that expiation for breaking an oath becomes due after the act?

If someone swears not to do something and then does it, they must offer expiation for breaking an oath, as Allah Almighty says: "So its expiation is the feeding of ten poor people from the average of that which you feed your [own] families or clothing them or freeing a slave. But he who finds not [the means to do so] - then a fast of three days." For feeding, it is sufficient to give each poor person one and a half kilograms of rice or flour, or a lunch or dinner meal. Ignorance of the necessity of expiation is not an excuse for its annulment.