Muwatta Malik
Book 36, Hadith 50
Arabic hadith text
وَحَدَّثَنِي مَالِكٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ وَهُوَ مُسْنِدٌ ظَهْرَهُ إِلَى الْكَعْبَةِ مَنْ أَخَذَ ضَالَّةً فَهُوَ ضَالٌّ .
Translation
Malik related to me from Yahya ibn Said from Said ibn al-Musayyabthat Umar ibn al-Khattab said while he was leaning his back againstthe Kaba, "Whoever takes a stray is astray."