While we were praying (Jumua Khutba & prayer) with the Prophet ﷺ, some camels loaded with food, arrived (from Sham). The people diverted their attention towards the camels (and left the mosque), and only twelve persons remained with the Prophet. So this verse was revealed: "But when they see Some bargain or some amusement, They disperse headlong to it, And leave you standing." (62.11)  

بَيْنَمَا نَحْنُ نُصَلِّي مَعَ النَّبِيِّ ﷺ إِذْ أَقْبَلَتْ عِيرٌ تَحْمِلُ طَعَامًا فَالْتَفَتُوا إِلَيْهَا حَتَّى مَا بَقِيَ مَعَ النَّبِيِّ ﷺ إِلاَّ اثْنَا عَشَرَ رَجُلاً فَنَزَلَتْ هَذِهِ الآيَةُ {وَإِذَا رَأَوْا تِجَارَةً أَوْ لَهْوًا انْفَضُّوا إِلَيْهَا وَتَرَكُوكَ قَائِمًا}