Matthew 4:10

Then Jesus told him, "Begone, Satan! it is written, You must worship the Lord your God, and serve him alone."

Luke 4:8

Jesus answered him, "It is written, You must worship the Lord your God, and serve him alone."

Matthew 6:24

No one can serve two masters: either he will hate one and love the other, or else he will stand by the one and despise the other ??you cannot serve both God and Mammon.

Matthew 15:8

This people honours me with their lips, but their heart is far away from me:

John 4:24

God is Spirit, and his worshippers must worship him in Spirit and in reality."

Treasury of Scripture Knowledge

Summary

And Samuel spake unto all the house of Israel, saying, If ye do return unto the LORD with all your hearts, then put away the strange gods and Ashtaroth from among you, and prepare your hearts unto the LORD, and serve him only: and he will deliver you out of the hand of the Philistines.

Bible References

Prepare

Matthew 15:8
This people honours me with their lips, but their heart is far away from me:
John 4:24
God is Spirit, and his worshippers must worship him in Spirit and in reality."

Serve him

Matthew 4:10
Then Jesus told him, "Begone, Satan! it is written, You must worship the Lord your God, and serve him alone."
Matthew 6:24
No one can serve two masters: either he will hate one and love the other, or else he will stand by the one and despise the other ??you cannot serve both God and Mammon.
Luke 4:8
Jesus answered him, "It is written, You must worship the Lord your God, and serve him alone."