Quran 2:225 Al-Baqarah, ayah 225 of 286

لَّا يُؤَاخِذُكُمُ ٱللَّهُ بِٱللَّغْوِ فِىٓ أَيْمَـٰنِكُمْ وَلَـٰكِن يُؤَاخِذُكُم بِمَا كَسَبَتْ قُلُوبُكُمْ ۗ وَٱللَّهُ غَفُورٌ حَلِيمٌ ۝٢٢٥

2:225 Allah will not take you to task for that which is unintentional in your oaths. But He will take you to task for that which your hearts have garnered. Allah is Forgiving, Clement.