Ambrose of Milan
Catena Aurea · Lukasevangelium 9
And he said to them all, If any man will come after me, let him deny himself, and take up his cross daily, and follow me. For whosoever will save his life shall lose it: but whosoever will lose his life for my sake, the same shall save it. For what is a man advantaged, if he gain the whole world, and lose himself, or be cast away? For whosoever shall be ashamed of me and of my words, of him shall the Son of man be ashamed, when he shall come in his own glory, and in his Father’s, and of the holy angels. But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God.
Now our Lord while He ever raises us to look to the future reward of virtue, and teaches us how good it is to despise worldly things, so also He supports the weakness of the human mind by a present recompense. For it is a hard thing to take up the cross, and expose your life to danger and your body to death; to give up what you are, when you wish to be what you are not; and even the loftiest virtue seldom exchanges things present for future. The good Master then, lest any man should be broken down by despair or weariness, straightway promises that He will be seen by the faithful, in these words, But I say unto you, There are some standing here who shall not taste of death till they see the kingdom of God.