On this verse, the Jewish commentary, Soncino, says that a person's good reputation, his name, is his most valuable asset. This is because of the integrity it took to produce it and the benefits it provides for one after he has it.
The Bible shows that God jealously guards His name and acts to ensure that it remains untarnished. His name represents what He is, and so it is with us as well. When we hear a name, images of what that person is immediately come to mind. In our mind's eye, we might recall a person as tall or short, male or female, learned or ignorant, black or white, angry or passive, beautiful or plain, vocal or quiet, honest or lying, responsible or irresponsible. Many character traits may flash through our minds in a moment or two.
The same happens to others as they think of us. What we project to others has everything to do with what we believe and practice. What kind of witness are we giving? Is what we believe and practice as true as God's Word?
Thus, if we want to have a good name in the eyes of God and man, we have to recognize truth, understand it and make it a part of us by submitting to it. This is where truth in a person's witness begins. If truth does not form the foundation of a person's life, the witness will reflect it.
Mankind—from Adam on—has been unwilling to do this. God says our "heart is deceitful above all things and [incurably sick (NKJV margin)]" (Jeremiah 17:9). We keep lying to ourselves and others, thus our name is not good before God. It means that to have this good name, we, as God's regenerated children, must face our vanities and stop deceiving ourselves that God will "just have to take us as we are." We need to quit blaming our failures, problems, and shortcomings on others, providing ourselves with justification for what we are and do.
Conduct is the "stuff" of which reputations are formed. Good conduct has truth at its foundation and integrity as its constant companion. From these two, a witness is produced. God wants our reputation before men to be built on His truth. Are we honestly doing this?