In Matthew 12 Jesus spoke of the Sabbath to the Pharisees.  They condemned Him because His disciples plucked corn on the Sabbath.
 

Matthew 12:1-2 At that time Jesus went on the Sabbath day through the corn; and his disciples were an hungered, and began to pluck the ears of corn and to eat.  But when the Pharisees saw it, they said unto him, Behold, thy disciples  do that which is not lawful to do upon the day.

 Jesus explained that David ate of the showbread in the house of God which was food reserved for the priests alone.
 
 

Matthew 12:3-4 But he said unto them, Have ye not read what David did, when he was an hungered, and they that were with him; How he entered into the house of God, and did eat the shewbread, which was not lawful for him to eat, neither for them which were with him, but only for the priests?

 Then He mentioned that even the law notes that a priest breaks the Sabbath every time he ministered, but all are blameless.
 

Matthew 12:5 Or have ye not read in the law, how that on the Sabbath days the priests in the temple profane the Sabbath, and are blameless?

 Here Jesus is talking about the temple in comparison to Him.  Being in the temple gave the priests free course to break the Sabbath.  Mow Christ is he who is greater than the temple.
 

Matthew 12:6 But I say unto you, That in this place is one  greater than the temple.

 Being in the temple gave the priests the special privilege of liberty which they had.  He is alluding to the fact that we can be in Him.  It has been the mercy of God that we have been freed from the restrictions of the Mosaic Law.
 

Romans 6:14 For sin shall not have dominion over you: for ye are not under the law, but under grace.

 Romans 7:3 So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man.

 The verse above shows the opportunity of being freed from the law of Moses.  There was a means of escaping the law!  Jesus Himself began explaining this very thing.
 

Matthew 12:7 But if ye had known what this meaneth, I will have mercy, and not sacrifice, ye would not have condemned the guiltless.

 Here Jesus referred to the verse spoken by Hosea.  It was a prophecy and a divine principle both.  Note the reference to "blameless" and "guiltless".  If one is blameless in breaking the law then one is above the law.  Paul said we are not under the law.

 The ones who were not understanding of what God was accomplishing for man's freedom from the law would not understand Hosea's prophecy.  The Son of Man is Lord of the Sabbath day.
 

Numbers 28:9-10 And on the Sabbath day two lambs of the first year without spot, and two tenth deals of flour for a meat offering mingled with oil, and the drink offering thereof; this is the burnt offering of every Sabbath, beside the continual burnt offering, and his drink offering.

 Offering a sacrifice on the Sabbath was work.  Yet it was blameless work.
 

Hosea 6:6 For I desired mercy and not sacrifice; and knowledge if God more than burnt offerings.

 Please notice how that Ho 6:6 mentions burnt offerings.

 Jesus used the same reference in Matt.  9:13
 

Matthew 9:13 But go ye and learn what that meaneth, I will have mercy, and not sacrifice: for I am not come to call the righteous, but sinners to repentance.

 The Pharisees asked why Jesus ate with publicans and sinners.  Jesus used that saying with reference to "they that are whole need not a physician."