وَعَنِ ابْنِ عُمَرَ أَنَّهُ قَالَ: مَنْ حَلَفَ عَلَى يَمِينٍ فَوَكَّدَهَا فَعَلَيْهِ عِتْقُ رَقَبَةٍ. أَخْرَجَ الأَوَّلَ مِنْ كِتَابِ الْكَفَّارَاتِ وَالنُّذُورِ، وَالثَّانِيَ وَالثَّالِثَ فِي كِتَابِ اخْتِلافِ مَالِكٍ وَالشَّافِعِيِّ رَضِيَ اللَّهُ عَنْهُمَا.
مسند امام شافی · Hadith 1725
On the authority of Ibn Omar, he said: Whoever takes an oath, asserts it, and then he has to free the neck. Take the first out of the Book of Atonement and Vows, and the second and third in the Book of the Difference of Malik and al-Shafi’i, may God be pleased with him.
Sanad
وَعَنِ ابْنِ عُمَرَ