Adam Clarke on Psalms 109:23

I am gone like the shadow - "I have walked like the declining shadow," - I have passed my meridian of health and life; and as the sun is going below the horizon, so am I about to go under the earth.

I am tossed up and down as the locust - When swarms of locusts take wing, and infest the countries in the east, if the wind happen to blow briskly, the swarms are agitated and driven upon each other, so as to appear to be heaved to and fro, or tossed up and down. Dr. Shaw, who has seen this, says it gives a lively idea of the comparisons of the psalmist.