"Six days shall work be done,
but on the seventh day is a Sabbath of solemn rest,
a holy convocation. You shall do no work.
It is a Sabbath to the LORD in all your dwelling places.
(Leviticus 23:3)
The Third Commandment takes us from acknowledgment to personalization to worship. Now that God has told us that He is the only true God and has given us His name, we're given the commandment regarding how we are to worship Him.
Sabbath, meaning rest, was a day that was dedicated to God. Anyone caught not dedicating the day to God was put to death. Why? Because the refusal to set aside time for God shows a refusal to let God reign in the heart. Refusal to let God reign in your heart shows the truest form of unbelief.
Unbelief doesn't allow for the proper worship of God. And what is proper worship? When we fear, love and trust in God so that we don't despise preaching and His Word, but hold it sacred and gladly hear it. That's proper worship: Gladly hearing and learn God's Word whenever and wherever you can. Amen.