Albert Barnes Commentary Psalms 49:2

"Both low and high, Rich and poor together." — Psalms 49:2 (ASV)

Both low and high - Those alike of humble and those of exalted rank, for it pertains equally to all. On the meaning of the “terms” employed here, see the notes at (Isaiah 2:9). These truths pertained to the “low,” that is, to those of humble rank, teaching them not to envy the rich and not to fear their power; and they pertained to those of exalted rank, teaching them not to trust in their riches and not to suppose that they could permanently possess and enjoy them.

Rich and poor together - For they are equally interested in these truths; that is, what the psalmist was about to say was adapted to impart useful lessons to both classes. Both needed instruction on the subject; and the same class of truths was adapted to furnish that instruction. The class of truths referred to was derived from the powerlessness of wealth in regard to the things of most importance to people, and from the fact that all that a person can gain must soon be left. These truths teach one class that they should not set their heart on wealth and should not pride themselves on possessing it, and they teach the other class that they should not envy or fear the possessor of riches.