Cyprian

What hope and reward remains for the righteous and for martyrs after the conflicts and sufferings of this present time, The Holy Spirit shows and predicts by Solomon, saying: "And although in the sight of men they suffered torments, yet their hope is full of immortality. And having been troubled in a few things, they shall be in many happily ordered, because God has tried them, and has found them worthy of Himself. …

Treatise XI Exhortation to Martyrdom Addressed to Fortunatus ↗

Gregory the Dialogist

Since then the holy Church has one time of persecution, another time of peace, our Lord has noticed both times in His command to us. For at the time of persecution we must lay down our soul, that is our life, which He signified, saying, Whosoever shall lose his life. But in time of peace, those things which have the greatest power to subdue us, our earthly desires, must be vanquished; which He signified, saying, What does it profit a man, &c. …

Catena Aurea by Aquinas ↗

Bede

For whoever wishes to save his life will lose it. But whoever loses his life for my sake will save it. Thus it is said to the faithful: Whoever wishes to save his life will lose it, and whoever loses his life for my sake will save it, as if it is said to the farmer: If you keep the grain, you lose it; if you sow it, you renew it. For who does not know that grain, when it is sown, perishes from sight and disappears in the earth? But from where it decays in the dust, it sprouts anew. …

On the Gospel of Luke ↗

Bonaventure

Secondly, he invites by consideration of one's own peril, when he says: For whoever wishes to save his soul shall lose it, that is, whoever wishes to save his life in the present shall lose his life in the future, namely for a momentary life he shall lose the eternal one: whence John 12: "He who loves his soul shall lose it"; because he who loves too much loves iniquitously, and "he who loves iniquity hates his own soul," as is said in the Psalm. …

Commentary on Luke, Chapter 9 ↗