Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1880
Jabir b. Abdullah reported: While the Apostle of Allah (may peace be upon him) was delivering (a sermon) on Friday, a caravan of merchandise came to Medina. The Companions of the Messenger of Allah (may peace be upon him) rushed towards it till only twelve persons were left with him including Abu Bakr and 'Umar; and it was at this occasion that this verse was revealed." And when they see merchandise or sport, they break away to it."