Keil & Delitzsch, on Ps 36:18

“The Lord knoweth the days of undefiled; and their inheritance shall be for ever.”

“The life of those who love Jahve with the whole heart is, with all its vicissitudes, an object of His loving regard and of His observant providential care, Psa 1:6; Psa 31:8, cf. Psa 16:1-11. He neither suffers His own to lose their heritage nor to be themselves lost to it. The αἰώνιος κληρονομία is not as yet thought of as extending into the future world, as in the New Testament. In Psa 37:19 the surviving refers only to this present life.”

Imported from an open dataset — not yet checked against the printed edition.