Matthew 4:10
Then saith Jesus to him, Be gone, Satan! for it is written, "Thou shalt worship the Lord thy God, and him only shalt thou serve."
Luke 4:8
And Jesus answering said to him, It is written, "Thou shalt worship the Lord thy God, and him only shalt thou serve."
Matthew 6:24
No one can serve two masters; for either he will hate one, and love the other; or else he will cleave to one, and despise the other. Ye cannot serve God and mammon.
Matthew 15:8
"This people honoreth me with their lips, but their heart is far from me.
John 4:24
God is a spirit; and they who worship must worship in spirit and in truth.