Adam Clarke on Matthew 26:31

All ye shall be offended - Or rather, Ye will all be stumbled - παντες υμεις σκανδαλισθησεσθε - ye will all forsake me, and lose in a great measure your confidence in me.

This night - The time of trial is just at hand.

I will smite the shepherd - It will happen to you as to a flock of sheep, whose shepherd has been slain - the leader and guardian being removed, the whole flock shall be scattered, and be on the point of becoming a prey to ravenous beasts.