Exodus 20 gives us this forgotten commandment, which begins with "Remember." This is the only one of the commandments that God must have believed we would forget.
Verse 8 says: "Remember the Sabbath day, to keep it holy."
What is the Sabbath day? The Sabbath day is the seventh day of the week.
Genesis 2:2: "And on the seventh day God ended his work which he had made: And he rested on the seventh day from all his work which he had made."
It is kept from sunset to sunset. (Genesis 1:5) Exodus 20:8-11 explains how God wants us to keep the Sabbath.
According to John 14:15, Jesus says, "If ye love me, keep my commandments." In John 15:10, Jesus says, "If ye keep my commandments, ye shall abide in my love; even as I have kept my Father's commandments, and abide in his love."
In Matthew 5:19, Jesus says, "Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called least in the kingdom of heaven: But whosoever shall do and teach them, the same shall be called great in the kingdom of heaven."
Isaiah 66:22-23 reads, "For as the new heavens and the new earth, which I will make, shall remain before me, saith the Lord, so shall your seed and your name remain. And it shall come to pass, that from one new moon to another, and from one Sabbath to another, shall all flesh come to worship before me, saith the Lord."
From this, one learns the Sabbath will be kept in the new earth.