Charles Ellicott Commentary Psalms 90:12

"So teach us to number our days, That we may get us a heart of wisdom." — Psalms 90:12 (ASV)

Number our days. —This verse, as it stands, literally translates: to allot, or in allotting , our days, so teach, and we will bring forth a heart of wisdom. The last clause, if intelligible at all, must mean, “that we may offer a wise heart.” The natural way to understand the verse is to make God, not man (as in the Authorized Version), the reckoner of the days: “In allotting our days, thus make us know (that is, make us know the power of Your anger), so that we may present a wise heart.”

The verse must evidently be taken in close connection with the preceding, or the point of the petition is lost. Although the ordinary rendering, “Teach us to number our days,” has given rise to a number of sayings that might be quoted as illustration, it is neither very intelligible in itself, nor can it be supported as a rendering of the original, except for one instance in later Hebrew.