Rejoice, and be exceedingly glad: for great is your reward in heaven: for so persecuted they the prophets who were before you.
All Commentaries on Matthew 5:12 Go To Matthew 5
Theophylact of Ochrid
AD 1107
Of the others whom He has said are blessed, He does not speak of a great reward. But here He does, to show that to patiently endure reviling is a great and most difficult thing; so difficult that there have been many who have even hanged themselves to escape this trial. Even Job, who patiently endured his other trials, was troubled when his friends reviled him by saying that he was suffering for his sins.
So that the apostles would not think that they would be persecuted for teaching something contrary to God, He exhorts them by saying, "Even the prophets before you were persecuted for the sake of virtue, and so you have the example of their sufferings to give you courage."