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."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَلِيَّ بْنَ أَبِي طَالِبٍ، قَالَ لاَ يَقْطَعُ الصَّلاَةَ شَىْءٌ مِمَّا يَمُرُّ بَيْنَ يَدَىِ الْمُصَلِّي ‏.‏
USC-MSA web (English) reference : Book 9, Hadith 43
Arabic reference : Book 9, Hadith 372