حَدَّثَنَا إِسْمَاعِيلُ حَدَّثَنَا أَيُّوبُ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ لَا أَعْلَمُهُ إِلَّا عَنْ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ مَنْ حَلَفَ فَاسْتَثْنَى فَهُوَ بِالْخِيَارِ إِنْ شَاءَ أَنْ يَمْضِيَ عَلَى يَمِينِهِ وَإِنْ شَاءَ أَنْ يَرْجِعَ غَيْرَ حَنِثٍ أَوْ قَالَ غَيْرَ حَرَجٍ
مسند امام احمد بن حنبل · Hadith 5093
It was narrated that Ibn 'Umar said - he (the narrator) said: I do not think but that it is from the Prophet (PBUH)-: "Whoever swears an oath and says in sha Allah has the choice: if he wishes he may go ahead and fulfil his oath, or if he wishes he can recant without being regarded as breaking his oath" - or he said, "with no problem."
Sanad
حَدَّثَنَا إِسْمَاعِيلُ حَدَّثَنَا أَيُّوبُ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ لَا أَعْلَمُهُ إِلَّا