Psalms 73:17 - Ellicott's Commentary On The Whole Bible

Then understood I... — Rather, I considered their end. The Temple service, with its blessings on righteousness, and stern warnings against wickedness, as they were read from the Book of the Law or from one of the prophets, or were chanted from some ancient song, gave the needed turn to the psalmist’s speculations. He began to think not of the present, but the future; not of the advantages of sin, but its consequences — but still consequences in this world, the thought of a hereafter not having established itself sufficiently to have an ethical force.