مُوَطَّأُ مَالِكٍ
Muwatta Malik 372
Shortening the Prayer
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَلِيَّ بْنَ أَبِي طَالِبٍ، قَالَ لاَ يَقْطَعُ الصَّلاَةَ شَىْءٌ مِمَّا يَمُرُّ بَيْنَ يَدَىِ الْمُصَلِّي .
Yahya related to me from Malik that he had heard that Ali ibn Abi Talib said, "Things that pass in front of a man praying do not break his prayer."
Arabic/English book reference: Book 9, Hadith 43