Narrated Ibn 'Umar (RA):

"Allah's Messenger (ﷺ) said: "Whoever swears an oath, and then says: "If Allah Wills", he is not held accountable if he breaks it." [Ahmad and al-Arba'a reported it, and Ibn Hibban graded it Sahih (authentic)].

وَعَنْ اِبْنِ عُمَرَ رَضِيَ اَللَّهُ عَنْهُمَا; أَنَّ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-قَالَ: {

مَنْ حَلِفِ عَلَى يَمِينٍ فَقَالَ: إِنْ شَاءَ اَللَّهُ, فَلَا حِنْثَ عَلَيْهِ

} رَوَاهُ اَلْخَمْسَةُ [1]‏ .‏ وَصَحَّحَهُ اِبْنُ حِبَّانَ [2]‏ .‏