In John 8:3-11 a women who was caught in adultery was brought to Jesus by the scribes and Pharisees and used to test Him. Jesus said to them "He who is without sin among you, let him throw the first stone at her." Instead of stoning her, they were convicted by their conscience and one by one they went out beginning with the oldest.
Now that I'm older it seems clearer why the oldest left first. We are not perfect. The older we get the more time we have to make mistakes. But hopefully we learn from them and become more compassionate towards others who make mistakes.
In Matthew 7:3-4 we are asked "Why do you see the speck that is in your brother's eye, but don't consider the beam that is in your own eye? Or how will you tell your brother, 'Let me remove the speck from your eye;' and behold, the beam is in your own eye?" It's easy to get angry at the sins of others and criticize them, and yet overlook our own sins. Think about it, when is the last time you criticized someone? Did they deserve it? If they did, were you harsh?
"Brothers, even if a man is caught in some fault, you who are spiritual must restore such a one in a spirit of gentleness; looking to yourself so that you also aren't tempted." Galatians 6:1
In addition, we must continue to forgive; "Then Peter came and said to him, "Lord, how often shall my brother sin against me, and I forgive him? Until seven times?" Jesus said to him, "I don't tell you until seven times, but, until seventy times seven." Matthew 18:21 Also, "For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you don't forgive men their trespasses, neither will your Father forgive your trespasses." Matthew 6:14-15.
Passages to consider: Matthew 18:23-35 and Colossians 3:12-13