Matthew 4:10
Then Jesus replied to him, "Get away from me Satan, for it is written [Deut. 6:13], 'You are supposed to worship the Lord your God, and serve only Him.'"
Luke 4:8
And Jesus answered him, "It is written [Deut. 6:13], 'You are supposed to worship the Lord, your God, and serve only Him.'"
Matthew 6:24
No person can serve two masters, for he will either hate the one and love the other, or else he will cling to the one and look down on the other. You cannot serve God and material things [at the same time].
Matthew 15:8
These people [claim to] honor me with their lips [i.e., by what they say], but their heart is far from [honoring] me.
John 4:24
God is Spirit and those who worship Him must worship in spirit and truth."