سُنَنُ ابْنِ مَاجَهْ
Sunan Ibn Majah 2105
The Chapters on Expiation
Uttering the exception when swearing
حَدَّثَنَا مُحَمَّدُ بْنُ زِيَادٍ، حَدَّثَنَا عَبْدُ الْوَارِثِ بْنُ سَعِيدٍ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ مَنْ حَلَفَ وَاسْتَثْنَى إِنْ شَاءَ رَجَعَ وَإِنْ شَاءَ تَرَكَ غَيْرُ حَانِثٍ .
It was narrated from Ibn 'Umar that the Messenger of Allah (ﷺ) said: "Whoever swears an oath and says In sha' Allah, if he wishes he may go ahead and if he wishes he may not, without having broken his oath."
Sunan Ibn Majah, 2105Sahih (Darussalam)