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 Authorised Version is quite right in taking the verbs in this clause as futures. (Comp. Psalms 37:11; Psalms 37:18; Psalms 37:22.) Emigration, when referred to by the prophets (Jeremiah 25:5; Jeremiah 35:15), is always represented as compulsory, and 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 allusion to their precarious condition, dependent as they were on offerings and tithes, but the Hebrew may also have the meanings: (1) Thou shalt feed on (or enjoy) stability (or security). (Comp. Isaiah 33:6 : “and wisdom and knowledge shall be the stability of thy times.”) (2) Thou shalt pasture on faithfulness, i.e., be supported by God’s truth and righteousness as by a rich pasture. (Comp. Psalms 23:1, and, for the expression, Proverbs 15:14, “feedeth on foolishness.”) Possibly both were combined in the psalmist’s thought, for the faithfulness of God is the security of man.