Arabic (Original)
حَدَّثَنَا يُونُسُ حَدَّثَنَا حَمَّادٌ يَعْنِي ابْنَ سَلَمَةَ عَنْ أَيُّوبَ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ إِذَا حَلَفَ أَحَدُكُمْ فَقَالَ إِنْ شَاءَ اللَّهُ فَهُوَ بِالْخِيَارِ إِنْ شَاءَ فَعَلَ وَإِنْ شَاءَ لَمْ يَفْعَلْ.
English Translation
Yunus told us, Hammad - that is, Ibn Salama - told us, from Ayyub, from Nafi', from Ibn Umar, that the Messenger of Allah, peace and blessings be upon him, said: "When one of you swears an oath and says, 'If Allah wills,' then he has a choice: if he wishes he may do it, and if he wishes he may not do it."