The Hebrew word for righteousness is tseh'-dek, tzedek, Gesenius's Strong's Concordance:6664—righteous, integrity, equity, justice, straightness. The root of tseh'-dek is tsaw-dak', Gesenius's Strong:6663—upright, just, straight, innocent, true, sincere. It is best understood as the product of upright, moral action in accordance with some form of divine plan.
In the Book of Job the title character is introduced to us as a person who is "perfect" in righteousness. This does not mean that he is sinless."Perfect" in this sense means that his righteousness permeates every relationship of his life as his working principle. After all, righteousness is a matter of relationships - with God, with things, and with other people. The biblical definition of righteousness involves the inherent quality of God. God is right because He is righteous, therefore God can only act righteously. In one instance the word means being right; in another it is used to mean doing right; in still another case it means putting right. Job qualifies as a righteous person on each of these counts, so much so that he is commended by God as "wholly righteous" or, translated into our terms, "perfect."
Righteousness as it is understood in the Old Testament is a thoroughly Hebraic concept at variance with the common understanding of the term. The failure to comprehend its meaning is perhaps the most responsible for the view of the Old Testament religion as legalistic and as far removed from the graciousness of the New Testament.