Muwatta Malik 1639

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ قَالَ سَمِعْتُ سَعِيدَ بْنَ الْمُسَيَّبِ، يَقُولُ أَلاَ أُخْبِرُكُمْ بِخَيْرٍ، مِنْ كَثِيرٍ مِنَ الصَّلاَةِ وَالصَّدَقَةِ قَالُوا بَلَى ‏.‏ قَالَ إِصْلاَحُ ذَاتِ الْبَيْنِ وَإِيَّاكُمْ وَالْبِغْضَةَ فَإِنَّهَا هِيَ الْحَالِقَةُ ‏.‏

Yahya related to me from Malik that Yahya ibn Said said that he heard Said ibn al-Musayyab say, "Shall I tell you what is better than much prayer and sadaqa?" They said, "Yes." He said, "Mending discord. And beware of hatred - it strips you (of your deen)

Reference

Muwatta Malik 1639

In-book

Book 47, Hadith 7