Old Testament readings use the Septuagint , the Scripture the apostles quoted. Masoretic numbering shown for reference.Learn why
LXX

Psalms 17:21

And the Lord will recompense me according to my righteousness; even according to the purity of my hands will he recompense me.

Parallel Translations

LXX2012View canonical →
For I have kept the way of the Lord and have not wickedly departed from my God.
Septuagint in American English (2012)