Prayer and fasting was first used by JESUS when the disciples could not professed micacle on the sick. Jesus came and did the wonders. Then the desciples question HIM why they could not do thessame and explained to them unless with fast and prayer, else, they could do anything. Some are fasting not just to obey their religious directive or obey the law of Moses in the old testament. Therefore, Jesus was referring to HIMSELF as bridegroom and not unless He departed from the them (the disciples) before they could perform fasting as others.