Matthew 5:22-24

But I say to you that everyone who continues to be angry with his brother or harbors malice against him shall be guilty before the court; and whoever speaks [contemptuously and insultingly] to his brother, ‘Raca (You empty-headed idiot)!’ shall be guilty before the supreme court (Sanhedrin); and whoever says, ‘You fool!’ shall be in danger of the fiery hell. So if you are presenting your offering at the altar, and while there you remember that your brother has something [such as a grievance or legitimate complaint] against you, leave your offering there at the altar and go. First make peace with your brother, and then come and present your offering.