that Messenger of Allah said: "If the one who passed in front of the person performing Salat knew what he was doing, then for him to stop (and wait for forty) would be better for him than to pass in front of him."  

سَمِعَ مِنْ رَسُولِ اللَّهِ ﷺ فِي الْمَارِّ بَيْنَ يَدَىِ الْمُصَلِّي فَقَالَ أَبُو جُهَيْمٍ قَالَ رَسُولُ اللَّهِ ﷺ لَوْ يَعْلَمُ الْمَارُّ بَيْنَ يَدَىِ الْمُصَلِّي مَاذَا عَلَيْهِ لَكَانَ أَنْ يَقِفَ أَرْبَعِينَ خَيْرٌ لَهُ مِنْ أَنْ يَمُرَّ بَيْنَ يَدَيْهِ قَالَ أَبُو النَّضْرِ لاَ أَدْرِي قَالَ أَرْبَعِينَ يَوْمًا أَوْ شَهْرًا أَوْ سَنَةً