Al-Ma'idah 5:89

لَا يُؤَاخِذُكُمُ ٱللَّهُ بِٱللَّغۡوِ فِيٓ أَيۡمَٰنِكُمۡ وَلَٰكِن يُؤَاخِذُكُم بِمَا عَقَّدتُّمُ ٱلۡأَيۡمَٰنَۖ فَكَفَّـٰرَتُهُۥٓ إِطۡعَامُ عَشَرَةِ مَسَٰكِينَ مِنۡ أَوۡسَطِ مَا تُطۡعِمُونَ أَهۡلِيكُمۡ أَوۡ كِسۡوَتُهُمۡ أَوۡ تَحۡرِيرُ رَقَبَةٖۖ فَمَن لَّمۡ يَجِدۡ فَصِيَامُ ثَلَٰثَةِ أَيَّامٖۚ ذَٰلِكَ كَفَّـٰرَةُ أَيۡمَٰنِكُمۡ إِذَا حَلَفۡتُمۡۚ وَٱحۡفَظُوٓاْ أَيۡمَٰنَكُمۡۚ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ لَكُمۡ ءَايَٰتِهِۦ لَعَلَّكُمۡ تَشۡكُرُونَ 89

Allah will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allah make clear to you His verses that you may be grateful