Theophylact of Ohrid
Catena Aurea · Lukasevangelium 22
And there appeared an angel unto him from heaven, strengthening him. And being in an agony he prayed more earnestly: and his sweat was as it were great drops of blood falling down to the ground. And when he rose up from prayer, and was come to his disciples, he found them sleeping for sorrow. And said unto them, Why sleep ye? rise and pray, lest ye enter into temptation.
Or this is proverbially said of one who has sweated intensely, that He sweated blood; the Evangelist then wishing to shew that He was moistened with large drops of sweat, takes drops of blood for an example. But afterwards finding His disciples asleep for sorrow, He upbraids them, at the same time reminding them to pray; for it follows, And when he rose from prayer and was come to his disciples, he found them sleeping.