Lead me in thy truth, and teach me. "Thy truth" would seem to mean here "the true, right path"—the "way of godliness." The prayer is that God will both teach this to the psalmist and "lead him in it"—cause him, i.
e; to walk in it, and never stray from it, so long as he lives. For thou art the God of my salvation. Thou art the God from whom alone I obtain salvation, and to whom alone, therefore, I am bound to pray for everything on which salvation depends—as, for instance, light and guidance.
On thee do I wait all the day. In prayer for these blessings, I wait on thee all the day long.