Charles Ellicott Commentary Psalms 71:18

"Yea, even when I am old and grayheaded, O God, forsake me not, Until I have declared thy strength unto [the next] generation, Thy might to every one that is to come." — Psalms 71:18 (ASV)

Now also when. —Literally, indeed, even to old age and grey hairs.Psalms 129:1 shows that this may be a national as well as an individual prayer.

Thy strength. —Literally, your arm, the symbol of power. (Isaiah 53:1, and similar passages.)

Unto this generation. —Literally, to a generation, explained by the next clause to mean, to the coming generation.