وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي النَّضْرِ، مَوْلَى عُمَرَ بْنِ عُبَيْدِ اللَّهِ عَنْ بُسْرِ بْنِ سَعِيدٍ، أَنَّ زَيْدَ بْنَ خَالِدٍ الْجُهَنِيَّ، أَرْسَلَهُ إِلَى أَبِي جُهَيْمٍ يَسْأَلُهُ مَاذَا سَمِعَ مِنْ، رَسُولِ اللَّهِ صلى الله عليه وسلم فِي الْمَارِّ بَيْنَ يَدَىِ الْمُصَلِّي فَقَالَ أَبُو جُهَيْمٍ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لَوْ يَعْلَمُ الْمَارُّ بَيْنَ يَدَىِ الْمُصَلِّي مَاذَا عَلَيْهِ لَكَانَ أَنْ يَقِفَ أَرْبَعِينَ خَيْرًا لَهُ مِنْ أَنْ يَمُرَّ بَيْنَ يَدَيْهِ ‏"‏ ‏.‏ قَالَ أَبُو النَّضْرِ لاَ أَدْرِي أَقَالَ أَرْبَعِينَ يَوْمًا أَوْ شَهْرًا أَوْ سَنَةً ‏.‏

Yahya related to me from Malik from Abu'n Nadr, the mawla of Umaribn Ubaydullah from Busr ibn Said that Zayd ibn Khalid al-Juhani senthim to Abu Juhaym to ask him what he had heard from the Messenger ofAllah, may Allah bless him and grant him peace, about passing in frontof someone praying. Abu Juhaym said, "The Messenger of Allah, mayAllah bless him and grant him peace, said, 'If the one who passes infront of a man praying knew what he was bringing upon himself it wouldbe better for him to stop for forty than to pass in front of him.' " Abu'n-Nadr said, "I do not know whether he said forty days ormonths or years." Translation Not Available

Book Ref: Muwatta Imam Malik Book 9 Hadith 366
Web Ref:  Muwatta Imam Malik Book 9 Hadith 37