God did not rest as a result of tiredness because He does not get weary (Isaiah 40:28). In this, man is unlike God. We need to rest this physical body on the Sabbath. This ties the rhythm of our bodies to the rhythm in which God made the world. God rested from the achievement of the physical creation, but that does not indicate His rest means inactivity because God nurtures what He creates. This is why Jesus said that His Father is working. The Sabbath is especially a time of spiritual activity that the Father spends preparing His children for His Kingdom.
The Bible says He blessed the Sabbath day. To bless is to favor. According to the Theological Wordbook of the Old Testament, the Hebrew word means "to endue with power for success, prosperity, fecundity, longevity, etc." Does God point out the fact that the proper observance of the Sabbath will go a long way toward promoting success in those who keep it? Yes, because He also sanctified it, consecrated it, hallowed it. He made it HOLY TIME!
It takes a holy God to make holy time, and this holy God made no time holy other than His Sabbaths. God can make man holy, but man cannot make anything holy. All of this is seen within the context of the seventh day, a specific day following the first six days of creation. Using any day other than the seventh day, the Sabbath, for the normal weekly worship of God is man-directed, and is neither blessed nor holy.
That the Sabbath is holy means it is worthy of respect, deference, even devotion not given other periods of time. It is set apart for sacred use because it is derived from God's own acts of creation and commands. The overall idea of the word holy is "different." Its root word means "cut," indicating "cut out," "separate," or in more modern terms, "a cut above." When it applies to God or those persons or objects He declares holy, a thing that is holy is different from the common. It is thus separate from others, cut out from the ordinary, or a cut above, indicating transcendence.