Jesus said "I came to fulfill the law and the prophets". Matt 5:17 "Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil."
Also we need to understand that during His time walking through Galilee, he went to SYNAGOGUES... He went to the towns where JEWS lived. Matt 15:24 "... I am not sent but unto the lost sheep of the house of Israel."
This does not mean that only Jews could be saved, but that He was sent as the last chance for reconciliation of the Israelite nation to God, before their judgment (in 70 AD). Matt 23:37 "O Jerusalem, Jerusalem, thou that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not!"
So, seeing that everything seems to point to Christ intentionally reaching out to the Jews during His ministry, it also makes sense that He would keep the Mosaic Law... if He didn't, none of the Jews would have accepted Him as God's Son, the Messiah.
But also, when we consider what happened in 70 AD... the temple was destroyed so there was literally NO WAY to fulfill the Mosaic Law anymore. This helps us understand how Christ "fulfilled the law" - His sacrifice was the most massive thing that ever happened... it was what all the practices of the law POINTED to... they foreshadowed it! That was why they did the sacrifices! God wanted them to KNOW that the Messiah was coming to shed His blood for everyone! The sacrifices really meant nothing - except to project the coming Messiah, and test the faith of the Israelites. God says He despised their sacrifices. Amos 5:21 I hate, I despise your feast days, and I will not smell in your solemn assemblies. 5:22 Though ye offer me burnt offerings and your meat offerings, I will not accept them:
So Christ really DID fulfil the law and the prophets! That is why we know we do not have to worry about practicing that Law any more. We really are under grace, covered by Christ's blood... He was given because God so loved the "cosmos" (in the Greek, John 3:16).
Suggests that Christians were to heartily abandon the Sabbath practices.
If, therefore, those who were brought up in the ancient order of things have come to the possession of a new hope, no longer observing the Sabbath, but living in the observance of the Lord’s Day, on which also our life has sprung up again by Him and by His death—whom some deny, by which mystery we have obtained faith,683 and therefore endure, that we may be found the disciples of Jesus Christ, our only Master—how shall we be able to live apart from Him, whose disciples the prophets themselves in the Spirit did wait for Him as their Teacher? And therefore He whom they rightly waited for, being come, raised them from the dead.
In Chp X, Judaizing is addressed.
It is absurd to profess Christ Jesus, and to Judaize. For Christianity did not embrace Judaism, but Judaism Christianity, that so every tongue which believeth might be gathered together to God.
Leviticus 12 and 15
Says that the reason for the 7 days of purification for a male childbirth and the 14 days for a female, is symbolic of the fact that Adam was created during the first week of creation (first 7 days), and that Eve was made from Adam's rib during the second week after creation.
3:4 And the Lord said unto us: 'It is not good that the man should be alone: let us make a helpmeet for him.'
3:5 And the Lord our God caused a deep sleep to fall upon him, and he slept, and He took for the woman one rib from amongst his ribs, and this rib was the origin of the woman from amongst his ribs, and He built up the flesh in its stead, and built the woman.
3:6 And He awaked Adam out of his sleep and on awaking he rose on the sixth day, and He brought her to him, and he knew her, and said unto her: 'This is now bone of my bones and flesh of my flesh; she shall be called [my] wife; because she was taken from her husband.'
3:7 Therefore shall man and wife be one and therefore shall a man leave his father and his mother, and cleave unto his wife, and they shall be one flesh.
3:8 In the first week was Adam created, and the rib -his wife: in the second week He showed her unto him: and for this reason the commandment was given to keep in their defilement, for a male seven days, and for a female twice seven days.
3:9 And after Adam had completed forty days in the land where he had been created, we brought him into the garden of Eden to till and keep it, but his wife they brought in on the eightieth day, and after this she entered into the garden of Eden.
3:10 And for this reason the commandment is written on the heavenly tablets in regard to her that gives birth: 'if she bears a male, she shall remain in her uncleanness seven days according to the first week of days, and thirty and three days shall she remain in the blood of her purifying, and she shall not touch any hallowed thing, nor enter into the sanctuary, until she accomplishes these days which (are enjoined) in the case of a male child.
3:11 But in the case of a female child she shall remain in her uncleanness two weeks of days, according to the first two weeks, and sixty-six days in the blood of her purification, and they will be in all eighty days.'
3:12 And when she had completed these eighty days we brought her into the garden of Eden, for it is holier than all the earth besides and every tree that is planted in it is holy.
"For if we still live according to the Jewish law, we acknowledge that we have not received grace. For the divinest prophets lived according to Christ Jesus."