Al-Ma'idah 5:89 لا يواخذكم الله باللغو في ايمانكم ولاكن يواخذكم بما عقدتم الايمان فكفارته اطعام عشرة مساكين من اوسط ما تطعمون اهليكم او كسوتهم او تحرير رقبة فمن لم يجد فصيام ثلاثة ايام ذالك كفارة ايمانكم اذا حلفتم واحفظوا ايمانكم كذالك يبين الله لكم اياته لعلكم تشكرون ٨٩

Allah does not take you to task for the oaths you utter vainly, but He will certainly take you to task for the oaths you have sworn in earnest. The expiation (for breaking such oaths) is either to feed ten needy persons with more or less the same food as you are wont to give to your families, or to clothe them, or to set free from bondage the neck of one man; and he who does not find the means shall fast for three days. This shall be the expiation for your oaths whenever you have sworn (and broken them.)¹ But do keep your oaths.² Thus does Allah make clear to you His commandments; maybe you will be grateful.