Matthew 12:7

But if ye had known what this meaneth.

They ought to have known, for they professed to be interpreters of the law, but in their slavery to forms and traditions, they had been blind to the spirit of the Scriptures.

I will have mercy and not sacrifice.

The argument is, that mercy toward these hungering disciples was more acceptable to God than sacrifices at the altar; though sacrifice was the crown of all the Jewish rites. The quotation is from Hosea 6:6, and is also quoted in Matthew 9:13. It shows that all our forms, rites and ceremonies are worthless before God unless we have kind and merciful hearts.