Al-Máida 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

Allāh will not impose blame upon you for what is meaningless¹ in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation² 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.³ Thus does Allāh make clear to you His verses [i.e., revealed law] that you may be grateful.

Allah will not call you to account for your thoughtless oaths, but He will hold you accountable for deliberate oaths. The penalty for a broken oath is to feed ten poor people from what you normally feed your own family, or to clothe them, or to free a bondsperson. But if none of this is affordable, then you must fast three days. This is the penalty for breaking your oaths. So be mindful of your oaths. This is how Allah makes things clear to you, so perhaps you will be grateful.