Allah does not hold you accountable for your laghw (ineffectual) oaths, but He does hold you accountable for the oath with which you have bound yourself. Its expiation is to feed ten poor persons at an average of what you feed your family with, or to clothe them, or to free a slave. However, if someone cannot afford, he has to fast for three days. That is expiation for the oaths that you have sworn. Take care of your oaths. That is how Allah makes His signs clear to you, so that you may be grateful.