Why do we worship on the first day of the week? The Old Testament command to observe the sabbath actually gave no provision to worship on that day, but rather to rest from work and to meditate upon the salvation of God. In the New Testament, Christ fulfilled all the law and He is the ultimate fulfillment of our Rest. Jesus finished the work of salvation and therefore we can rest in the fact that the work is complete, as Jesus himself rested as he sat down upon the right hand of God after the offering was complete.