Psalms 91:4

He shall cover thee with his feathers - He shall act towards thee as the hen does to her brood, - take thee under his wings when birds of prey appear, and also shelter thee from chilling blasts. This is a frequent metaphor in the sacred writings; see Psalm 17:8 (note), Psalm 57:1 (note), Psalm 61:4 (note), and the notes on them. The Septuagint has Εν τοις μεταφρενοις αυτου επισκιασει σοι· He will overshadow thee between his shoulders; alluding to the custom of parents carrying their weak or sick children on their backs, and having them covered even there with a mantle. Thus the Lord is represented carrying the Israelites in the wilderness. See Deuteronomy 32:11-12 (note), where the metaphor is taken from the eagle.

His truth shall be thy shield and buckler - His revelation; his Bible. That truth contains promises for all times and circumstances; and these will be invariably fulfilled to him that trusts in the Lord. The fulfillment of a promise relative to defense and support is to the soul what the best shield is to the body.

He shall cover thee with his feathers ... - As the parent bird protects its young. See the notes at Psalm 17:8. Compare Deuteronomy 32:11. "His truth." His unfailing promise; the certainty that what he has promised to do he will perform.

Shall be thy shield and buckler - literally, "Shield and buckler is his truth." The meaning is, that his pledge or promise would be unto them as the shield of the soldier is to him in battle. Compare Psalm 35:2. The word rendered "buckler" is derived from the verb "to surround," and is given to the defensive armor here referred to, because it "surrounds," and thus "protects" a person. It may apply to a coat of mail.