At first glance, Psalm 26 sounds like David is a braggart: ‘ I have walked in my integrity, and I have trusted in the LORD without wavering.”  Puritan Thomas Brooks, in his book Precious Remedies Against Satan’s Devices (p54), points out, however, that David is claiming that God’s mercy and lovingkindness have empowered him to avoid sin.

Verse 3 says “For your steadfast love is before my eyes, and I walk in your faithfulness.”  It is by God’s steadfast love and God’s faithfulness that David is able to say:

–          I do not sit with men of falsehood

–          I do not consort with hypocrites

–          I hate the assembly of evildoers

–          I will not sit with the wicked

–          I proclaim thanksgiving aloud

–          I tell all your wondrous deeds

–          I love the place where your glory dwells

So, indeed, David is boasting.  But he boasts about the LORD, in whose power he walks.  God’s mercy protects him from sin; it does not encourage him to sin.