From the Directory of Public Worship, I.1
By the works of His hands, and the word of His mouth, God calls all mankind to worship and serve Him. In His being and works God is most worthy of worship. He is the creator and sustainer of all who live; therefore, every person should honor Him as God and give Him thanks (Ps. 95, Ps. 96, Rom. 1:18-23). Indeed, whether we eat or drink, or whatever we do, we should do all to the glory of God (1 Cor. 10:31). By the mercies shown to them, those redeemed in Christ are especially called to worship and serve God (Rom. 12:1-2).
From the Directory of Public Worship, II.1
The God who calls us to worship also directs us how to worship. The Word of God given to us in the Holy Scriptures is the only rule to direct us in how we may worship and glorify Him. What He commands us, we must do, neither adding to nor taking away from anything which He commands (Deut. 12:29-32, LC Q. 109).