"Whoever swears an oath and says, 'If Allah wills,' then he has the choice: If he wishes, he may go ahead, and if he wishes he may not." (Using translation from Nasāʾī 3830)
النَّبِيَّ ﷺ قَالَ مَنْ حَلَفَ عَلَى يَمِينٍ فَقَالَ إِنْ شَاءَ اللهُ فَهُوَ بِالْخِيَارِ إِنْ شَاءَ فَلْيَمْضِ وَإِنْ شَاءَ فَلْيَتْرُكْ