سُنَنُ النَّسَائِيِّ
Sunan an-Nasa’i 3793
The Book of Oaths and Vows
Whoever Swears An Oath And Says: "If Allah Wills"
أَخْبَرَنِي أَحْمَدُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا حِبَّانُ، قَالَ حَدَّثَنَا عَبْدُ الْوَارِثِ، قَالَ حَدَّثَنَا أَيُّوبُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ مَنْ حَلَفَ فَاسْتَثْنَى فَإِنْ شَاءَ مَضَى وَإِنْ شَاءَ تَرَكَ غَيْرَ حَنِثٍ .
It was narrated from Ibn 'Umar that the Prophet (ﷺ) said: "Whoever swears an oath and says: 'If Allah wills', then if he wishes he may go ahead, and if he wishes he may not, without having broken his oath."
Sunan an-Nasa'i, 3793sahih (Darussalam)