Sahih Al Bukhari Hadith Number 936

Narrated Jabir bin `Abdullah: While we were praying (Jumua Khutba & prayer) with the Prophet (peace be upon him), 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)

11  Friday Prayer
Hadith number 936
Volume no 2
Chapter: 38 (If some people leave while the Imam during the Salat-ul-Jumu’ah)