Stop Using Matthew 12 to justify cooking and buying on the Sabbath
Matthew 12:1 At that time Jesus went on the sabbath day through the corn; and his disciples were an hungred, 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 sabbath day.
Was it unlawful to pluck corn to eat on the sabbath if you were poor or was it unlawful to gather corn to store on the sabbath day?
Answer- Leviticus 19:9 And when ye reap the harvest of your land, thou shalt not wholly reap the corners of thy field, neither shalt thou gather the gleanings of thy harvest.10 And thou shalt not glean thy vineyard, neither shalt thou gather every grape of thy vineyard; thou shalt leave them for the poor and stranger: I am the LORD your God.
Matthew 12:3 But he said unto them, Have ye not read what David did, when he was an hungred, 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?
Answer- David was on the run from king Saul and his men had not eaten for days it was a matter of life or death.
1 Samuel 21:1-10 And David arose, and fled that day for fear of Saul, and went to Achish the king of Gath.
Mark 3:4 And he saith unto 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 12:5 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?
Answer- John 7:22 “Moses therefore gave unto you circumcision; (not because it is of Moses, but of the fathers;) and ye on the sabbath day circumcise a man.23 If a man on the sabbath day receive circumcision, that the law of Moses should not be broken; are ye angry at me, because I have made a man every whit whole on the sabbath day?”
They also sacrificed
Numbers 28:10 This is the burnt offering of every sabbath, beside the continual burnt offering, and his drink offering.
Peace and Blessings to you and yours.