The Son of man is Lord - See on Matthew 12:7, Matthew 12:8 (note). Some have understood this as applying to men in general, and not to Christ. The Son of man, any man is Lord of the Sabbath; i.e. it was made for him, for his ease, comfort, and use, and to these purposes he is to apply it. But this is a very harsh, and at the same time a very lax, mode of interpretation; for it seems to say that a man may make what use he pleases of the Sabbath; and, were this true, the moral obligation of the Sabbath would soon be annihilated.

God ordained the Sabbath not only to be a type of that rest which remains for the people of God, but to be also a mean of promoting the welfare of men in general.

The ordinances of religion should be regulated according to their end, which is the honor of God, and the salvation of men. It is the property of the true religion to contain nothing in it but what is beneficial to man. Hereby God plainly shows that it is neither out of indigence or interest that he requires men to worship and obey him; but only out of goodness, and to make them happy. God prohibited work on the Sabbath day, lest servants should be oppressed by their masters, that the laboring beasts might have necessary rest, and that men might have a proper opportunity to attend upon his ordinances, and get their souls saved. To the Sabbath, under God, we owe much of what is requisite and necessary as well for the body as the soul.

Mark 3:4 And he said to them, Is it lawful to do good on the sabbath days, or to do evil? to save life, or to kill? But they held their peace.

Matthew 12:8 For the Son of man is Lord even of the sabbath day.

Luke 6:5 And he said to them, That the Son of man is Lord also of the sabbath.

Luke 13:15,16 The Lord then answered him, and said, You hypocrite, does not each one of you on the sabbath loose his ox or his donkey from the stall...

John 5:9-11,17 And immediately the man was made whole, and took up his bed, and walked: and on the same day was the sabbath...

John 9:5-11,14,16 As long as I am in the world, I am the light of the world...

Ephesians 1:22 And has put all things under his feet, and gave him to be the head over all things to the church,

Revelation 1:10 I was in the Spirit on the Lord's day, and heard behind me a great voice, as of a trumpet,

Christ's Authority to Forgive
'And again He entered into Capernaum after some days; and it was noised that He was in the house. 2. And straightway many were gathered together, insomuch that there was no room to receive them, no, not so much as about the door; and He preached the word unto them. 3. And they come unto Him, bringing one sick of the palsy, which was borne of four. 4. And when they could not come nigh unto Him for the press, they uncovered the roof where He was: and when they had broken it up, they let down the bed …
Alexander Maclaren—Expositions of Holy Scripture

The Call and Feast of Levi
"And He went forth again by the seaside; and all the multitude resorted unto Him, and He taught them. And as He passed by, He saw Levi the son of Alphaeus sitting at the place of toll, and He saith unto him, Follow Me. And he arose and followed Him. And it came to pass, that He was sitting at meat in his house, and many publicans and sinners sat down with Jesus and His disciples: for there were many, and they followed Him. And the scribes of the Pharisees, when they saw that He was eating with the …
G. A. Chadwick—The Gospel of St. Mark

The Sabbath
"And it came to pass, that He was going on the sabbath day through the cornfields; and His disciples began, as they went, to pluck the ears of corn. And the Pharisees said unto Him, Behold, why do they on the sabbath day that which is not lawful? And He said unto them, Did ye never read what David did, when he had need, and was an hungered, he, and they that were with him? How he entered into the house of God when Abiathar was high priest, and did eat the shewbread, which it is not lawful to eat …
G. A. Chadwick—The Gospel of St. Mark