Cyril of Alexandria
Catena Aurea · Lukasevangelium 6
And it came to pass in those days, that he went out into a mountain to pray, and continued all night in prayer to God. And when it was day, he called unto him his disciples: and of them he chose twelve, whom also he named apostles; Simon, (whom he also named Peter,) and Andrew his brother, James and John, Philip and Bartholomew, Matthew and Thomas, James the son of Alphæus, and Simon called Zelotes, And Judas the brother of James, and Judas Iscariot, which also was the traitor.
Let us examine then in the actions which Jesus did, how He teaches us to be instant in prayer to God, going apart by ourselves, and in secret, no one seeing us; putting aside also our worldly cares, that the mind may be raised up to the height of divine contemplation; and this we have marked in the fact, that Jesus went in to a mountain apart to pray.