My brother complained to me about a girl who knows him very well. She came to his work place but did not greet him. He was not happy because it showed disrespect in his opinion. (The lady is younger than him.) He also said that if he is in a position to offer assistance to her while she came there he might not have. I pointed out to him that not greeting a person is not a sin but is needed in having a healthy relationship with others. What do you think?
"But I say to you, do not resist an evil person; but whoever slaps you on your right cheek, turn the other to him also. If anyone wants to sue you and take your shirt, let him have your coat also. Whoever forces you to go one mile, go with him two. Give to him who asks of you, and do not turn away from him who wants to borrow from you" (Matthew 5:39-42).
Jesus is speaking about those who purposely cause you hardship. His answer was not to take revenge, but go out of your way to do more for the person than he might expect. "Repay no one evil for evil. Respect what is honorable in the sight of all men. If it is possible, as much as it is up to you, be at peace with all men. Don't seek revenge yourselves, beloved, but give place to God's wrath. For it is written, "Vengeance belongs to me; I will repay, says the Lord." Therefore "If your enemy is hungry, feed him. If he is thirsty, give him a drink; for in doing so, you will heap coals of fire on his head." Don't be overcome by evil, but overcome evil with good" (Romans 12:17-21).
Your brother has no idea why this young lady neglected to greet him. She could have been having a really bad day. She might have been focused on something else. She could have simply not noticed him. In other words, there is no reason to assume she did this out of meanness to slight him. But even if she did, Jesus' answer is that he should go out of his way to treat her well, if for no other reason than that she will be embarrassed that she treated him so poorly.