2 Samuel 22:26 in the World English Bible
With the merciful you will show yourself merciful. With the perfect man you will show yourself perfect.
Context
25 Therefore the LORD hath recompensed me according to my righteousness; according to my cleanness in his eye sight.
26 With the merciful thou wilt shew thyself merciful, and with the upright man thou wilt shew thyself upright.
27 With the pure thou wilt shew thyself pure; and with the froward thou wilt shew thyself unsavoury.