Charles Ellicott Commentary Psalms 37:3

"Trust in Jehovah, and do good; Dwell in the land, and feed on [his] faithfulness." — Psalms 37:3 (ASV)

The alphabetic structure helps the poet to make an emphatic threefold exhortation to piety: Trust in Jehovah; commit thy way to Jehovah; rest in Jehovah.

So shalt thou dwell ... — The Authorized Version is quite right in taking the verbs in this clause as futures. (Compare to Psalm 37:11, Psalms 37:18, and Psalm 37:22.) Emigration, when referred to by the prophets (Jeremiah 25:5 and Jeremiah 35:15), is always represented as compulsory. It was a promise of preservation from it, not a warning against it, that the pious Israelite needed.

And verily thou shalt be fed. — Taken literally, this promise may be addressed to the Levites and may contain an allusion to their precarious condition, as they were dependent on offerings and tithes. However, the Hebrew may also have these meanings:

1. Thou shalt feed on (or enjoy) stability (or security). (Compare to Isaiah 33:6: and wisdom and knowledge shall be the stability of thy times.)
2. Thou shalt pasture on faithfulness, that is, be supported by God’s truth and righteousness as by a rich pasture. (Compare to Psalm 23:1, and for the expression, Proverbs 15:14: feedeth on foolishness.)

Possibly both meanings were combined in the psalmist’s thought, for the faithfulness of God is the security of man.