What was the purpose of the sermon given by the Prophet Muhammad (saw) on the particular Friday when the caravan from Syria arrived and caused the people to flock away, leaving only twelve people, as mentioned in the hadith?
 Jabir b. Abdullah reported that the Apostle (may peace be upon him) was delivering the sermon on Friday in a standing posture when a caravan from Syria arrived. The people flocked towards it till no one was left (with the Holy Prophet) but twelve persons, and it was on this occasion that this verse in regard to Jumu'a was revealed." And when they see merchandise or sport. they break away to it and leave thee standing."