Chapter 6:12-19 Choosing the Twelve

6:12 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.

We often think one half hour a great deal to spend in meditation and secret prayer, but Christ was whole nights engaged in these duties.

6:13 And when it was day, He called unto Him His disciples: and of them He chose twelve, whom also He named apostles;
And when it was day - Or morning; having spent the whole night in prayer to God, no doubt for His disciples, whom He was about to send forth as His apostles, to preach His Gospel, and work miracles, and for their success therein: He called unto Him His disciples - the whole company of them, whom he also named apostles; or "messengers".

6:14 Simon, (whom He also named Peter,) and Andrew his brother, James and John, Philip and Bartholomew,

Simon, whom He also named Peter - Which signifies a rock, or stone, and Andrew his brother; who was called at the same time with him, James and John: Philip and Bartholomew; the latter of these is by some thought to be Nathanael.

6:15 Matthew and Thomas, James the son of Alphaeus, and Simon called Zelotes,

Matthew and Thomas - The first of these was a publican, and who also was called Levi; and the latter had besides the name of Didymus, and was he that was so unbelieving of Christ's resurrection: James the son of Alphaeus; sometimes called James the less, and the brother of our Lord: and Simon called Zelotes; or the Canaanite;

6:16 And Judas the brother of James, and Judas Iscariot, which also was the traitor.

And Judas the brother of James - this Judas was also called Thaddaeus and Lebbaeus, and is the writer of the epistle that bears his name: and Judas Iscariot, which also was the traitor; both his surname and his character are mentioned, to distinguish him from the other Judas:

6:17 And He came down with them, and stood in the plain, and the company of His disciples, and a great multitude of people out of all Judaea and Jerusalem, and from the sea coast of Tyre and Sidon, which came to hear Him, and to be healed of their diseases;

--The whole picture is striking--

Jesus ascends a mountain, employs the night in prayer; 

and, having thus solemnly invoked the Divine blessing, authoritatively separates the twelve apostles from the mass of His disciples. 

He then descends, and heals in the plain all the diseased among a great multitude, collected from various parts by the fame of His miraculous power. 

Having thus created attention, He likewise satisfies the desire of the people to hear His doctrine; and retiring first to the mountain whence He came, that His attentive hearers might follow Him and might better arrange themselves before Him - All admire his excellent sayings with sacred silence.

6:18 And they that were vexed with unclean spirits: and they were healed.
And they that were vexed with unclean spirits - Were possessed with devils, and sadly tormented and afflicted by them:
and they were healed - both such that had bodily diseases, and were under diabolical possessions.

6:19 And the whole multitude sought to touch Him: for there went virtue out of Him, and healed them all.

for there went virtue out of Him; in great abundance, as water from a fountain; without his speaking a word, or using any gesture, such as laying His hands on them.