5 Having alarmed them therefore hereby, He comforts them also by His good things.
“For the Son of Man shall come,” says He, “in the glory of His Father with His holy angels, and then He shall reward every man according to his works.”
Do you see how the glory of the Father and of the Son is all one? But if the glory be one, it is quite evident that the substance also is one. For if in one substance there be a difference of glory (“for there is one glory of the sun, and another glory of the moon, and another glory of the stars; for one star differs from another star in glory;” although the substance be one), how may the substance of those differ, whereof the glory is one? For He said not at all, “In glory such as the Father's,” whereby you might suppose again some variation; but implying entire perfection, “In that same glory,” says He, “will He come;” for it to be deemed one and the same.
“Now, why fear, O Peter” (so He speaks), “on being told of death? Why, then shall you see me in the glory of the Father. And if I am in glory, so are you; your interests are no wise limited to the present life, but another sort of portion will take you up, a better one.” Nevertheless, when He had spoken of the good things, He stayed not at this, but mingled the fearful things also, bringing forward that judgment-seat, and the inexorable account, and the inflexible sentence, and the judgment that cannot be deceived.
He suffered not however His discourse to appear only dismal, but tempered it also with good hopes. For neither did He say, “then shall He punish them that sinned,” but, “He shall reward every man according to his doings.” And this He said, reminding not only the sinners of punishment, but also them that have done well of prizes and crowns.
Source: Homilies on the Gospel of St. Matthew (New Advent)