(6621) The Statement of Allah: “Allah will not punish you for what is unintentional in your oaths, but He will punish you for your deliberate oaths; for its expiation (a deliberate oath) feed ten poor persons, on a scale of the average of that with which you feed your own families; or clothe them; or manumit a slave. But whosoever cannot afford (that), then he should fast for three days. That is the expiation for the oath when you have sworn. And protect your oaths (i.e., do not swear much). Thus Allah make clear to you His Ayat (proofs, evidances, verses, lessons, signs, revelations, etc.) that you may be grateful. (V.5:89)
Narrated `Aisha: Abu Bakr As-Siddiq had never broken his oaths till Allah revealed the expiation for the oaths. Then he said, If I take an oath to do something and later on I find something else better than the first one, then I do what is better and make expiation for my oath.