"Therefore, if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there in front of the altar. First go and be reconciled to your brother; then come and offer your gift." (Matt 5)
With this statement, Jesus elevates our relationships to one another to be as important as "worship". No matter how much I give, sing and work, if I am not right with you, I am not right with God.