I will not know a wicked person.
Our friends can really get us into trouble. The Psalmist realized this and made the decision to not be friendly with wicked people. Anyone whose desires and interests are completely opposed to God can be classified as a wicked person. The Old Testament queen Jezebel was a wicked person. She deliberately did things that were against God and His people. Be very careful who you hang around with. Evil can be very subtle and it will catch you in its trap if you are not on constant guard.