Paul was not together with Christ disciples the day they had been foretold about the coming event and destruction of the temple in Jerusalem, so, he didnt hear Jesus word to pray that the destruction day would not fall on Sabbath day, in order the disciples might flee to safe their life.
But, did he understand that Sabbath keeping as written in the 4th commandment is an everlasting command?
How could he be different?
If Jesus, the Lord of the Sabbath has chosen him directly in a very specific way, why would Christ taught him differently than what he had taught his disciples? There is no reason to believe that Christ had taught Paul differently than what he had taught his 12 disciples. Paul understood clearly about the law of God and the weekly rest of the 4th commandment. He had not the slightest objection at all.
Galatians 2:20: I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
If Christ lived in Him, leading his life, his thinking, his doing, as what he had said: For it is God which worketh in you both to will and to do of his good pleasure (Phil. 2:13), is it possible that his teaching and ideas is promoting the eradication of the law of God, the nailing of the Sabbath commemoration on the cross of Christ? Only those who want to erect another sabbath, who want to change the law of God, would think so!
And who is the most person that want a change the law of God, to nail the Sabbath forever or change it with another day? Satan himself. Why? Because he knew, that those Sabbath keepers are believers that has the strongest and most intimate relationship with Christ, and their teaching to the world would endanger his mission.
Ezekiel 20:19, 20: I am the LORD your God; walk in my statutes, and keep my judgments, and do them. And hallow my sabbaths; and they shall be a sign between me and you, that ye may know that I am the LORD your God.
I am the Lord your God, is the Lord of the Sabbath.
Isaiah 58:13, 14: If thou turn away thy foot from the sabbath, from doing thy pleasure on my holy day; and call the sabbath a delight, the holy of the LORD, honourable; and shalt honour him, not doing thine own ways, nor finding thine own pleasure, nor speaking thine own words. Then shalt thou delight thyself in the LORD; and I will cause thee to ride upon the high places of the earth, and feed thee with the heritage of Jacob thy father: for the mouth of the LORD hath spoken it.
3 things Jesus promise to those who kept his Sabbath holy: 1. To delight in Him. 2. They will travel above the highest places on earth (when Christ took them at his 2nd coming to heaven). 3. They will eat the heritage of Jacob.
And what is the heritage of Jacob? Jeremiah 10:16: The portion of Jacob is not like them: for he is the former of all things; and Israel is the rod of his inheritance: The LORD of hosts is his name.
Praise God, the heritage of Jacob is Christ himself.
What a blessing to those Sabbath keepers.
And Satan knew this, and he tried hard to avert people eyes from the truth, and we can see it from all those hot debate about Sabbath here.