John Lightfoot on Matthew 9:15

[The children of the bridechamber.] The sons of the bridechamber, an ordinary phrase. There is no need to relate their mirth in the time of the nuptials: I will relate that only, and it is enough, which is spoke by the Glosser, They were wont to break glass vessels in weddings And that for this reason, that they might by this action set bounds to their mirth, lest they should run out into too much excess. The Gemara produceth one or two stories there: "Mar the son of Rabbena made wedding feasts for his son, and invited the Rabbins: and when he saw that their mirth exceeded its bounds, he brought forth a glass cup worth four hundred zuzees, and brake it before them; whereupon they became sad." The like story is also related of Rabh Ishai. And the reason of this action is given; Because it is forbidden a man to fill his mouth with laughter in this world.

...the days of the bridechamber, to the sons of the bridechamber, that is, to the friends and acquaintance, were seven: hence there is frequent mention of "the seven days of the marriage-feast": but to the bride, the days of the bridechamber were thirty. It is forbidden to eat, drink, wash or anoint oneself on the day of Expiation: But it is allowed a king and a bride to wash their faces "For the bride is to be made handsome (saith the Gloss upon the place), that she may be lovely to her husband. And all the thirty days of her bridechamber she is called The Bride."

It is worth meditation, how the disciples, when Christ was with them, suffered no persecution at all; but when he was absent, all manner of persecution overtook them.