Muwatta Malik 1022
Vows and Oaths
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ كَانَ يُكَفِّرُ عَنْ يَمِينِهِ، بِإِطْعَامِ عَشَرَةِ مَسَاكِينَ لِكُلِّ مِسْكِينٍ مُدٌّ مِنْ حِنْطَةٍ وَكَانَ يَعْتِقُ الْمِرَارَ إِذَا وَكَّدَ الْيَمِينَ .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to do kaffara for a broken oath by feeding ten poor people. Each person got a mudd of wheat. He sometimes freed a slave if he had repeated the oath
Grading: Salim al-Hilali: Mauquf Sahih
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.