עִם־חָסִ֥יד תִּתְחַסָּ֑ד עִם־גְּבַ֥ר תָּ֝מִ֗ים תִּתַּמָּֽם׃
With the merciful Thou dost show Thyself merciful, with the upright man Thou dost show Thyself upright;
Read Jewish philosophical commentary on Psalms 18:26: and classical philosophical sources.