And in these verses the reason is assigned, namely, his covenant engagements. See those scriptures in proof, Exodus 5:1; Numbers 21:21-25; Deuteronomy 7:22-23.
Related Commentaries of Psalms 135:13
Psalms 135:13-14
13 Thy name, O LORD, endureth for ever; and thy memorial, O LORD, throughout all generations.
14 For the LORD will judge his people, and he will repent himself concerning his servants.