But they that wait upon the Lord,.... As children on their parents, to do them honour, to obey their commands, and receive food and blessings from them; as servants on their masters, to know their pleasure, do their work, and have their wages; as clients on their patrons, to have advice of them, put their cause into their hands, and know how it goes; and as beggars at the door, who knock and wait, tell their case and wait, meet with repulses, yet keep their place, and continue waiting: such an act supposes a knowledge and reverence of God, confidence in him, attendance on him, not with the body only, in public and private, but with the soul also, and with some degree of constancy, and with patience and quietness: the Lord is to be waited upon for the manifestations of himself, who sometimes hides himself, but is to be waited for, since he has his set time to show himself again, and his presence is worth waiting for; also for the performance of his promises, which may be expected from his perfections, the nature of the promises, and their being in Christ; likewise for answers of prayer, and for the fresh discoveries of pardoning grace and mercy; and as Old Testament saints waited for the first coming of Christ, so New Testament saints for his second coming, and for eternal glory and happiness: and such "shall renew their strength"; which is to be understood of spiritual! strength in the heart, and of the graces of the Spirit there: it supposes strength received already, which natural men have not, but converted men have; and yet they want more, and more they shall have; to assist them in the performance of duty, to enable them to resist Satan and his temptations, and the corruptions of nature, and to cause them to endure afflictions and persecutions patiently, and to persevere unto the end:

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But they that wait upon the Lord - The word rendered 'wait upon' here (from קוה qâvâh), denotes properly to wait, in the sense of expecting. The phrase, 'to wait on Yahweh,' means to wait for his help; that is, to trust in him, to put our hope or confidence in him. It is applicable to those who are in circumstances of danger or want, and who look to him for his merciful interposition. Here it properly refers to those who were suffering a long and grievous captivity in Babylon, and who had no prospect of deliverance but in him. The phrase is applicable also to all who feel that they are weak, feeble, guilty, and helpless, and who, in view of this, put their trust in Yahweh. The promise or assurance here is general in its nature, and is as applicable to his people now as it was in the times of the captivity in Babylon. Religion is often expressed in the Scriptures by 'waiting on Yahweh,' that is, by looking to him for help, expecting deliverance through his aid, putting trust in him (see Psalm 25:3, Psalm 25:5, Psalm 25:21; Psalm 27:14; Psalm 37:7, Psalm 37:9, Psalm 37:34; Psalm 69:3; compare Isaiah 8:17, note; Isaiah 30:18, note).

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They shall mount zap with wings as eagles "They shall put forth fresh feathers like the moulting eagle" - It has been a common and popular opinion that the eagle lives and retains his vigor to a great age; and that, beyond the common lot of other birds, he moults in his old age, and renews his feathers, and with them his youth. "Thou shalt renew thy youth like the eagle, "says the psalmist, Psalm 103:5; on which place St. Ambrose notes, Aquila longam aetatem ducit, dum, vetustis plumis fatiscentibus, nova pennarum successione juvenescit: "The eagle lives to a very advanced age; and in moulting his youth is renewed with his new feathers." Phile, De Animalibus, treating of the eagle, and addressing himself to the emperor Michael Palaeologus junior, raises his compliment upon the same notion: -

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But they that wait upon the LORD shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.

40:31 Wait - That rely upon him. Renew - Shall grow stronger and stronger.

renew: Heb. change

31. mount up-(2Sa 1:23). Rather, "They shall put forth fresh feathers as eagles" are said to renovate themselves; the parallel clause, "renew their strength," confirms this. The eagle was thought to moult and renew his feathers, and with them his strength, in old age (so the Septuagint, Vulgate, Ps 103:5). However, English Version is favored by the descending climax, mount up-run-walk; in every attitude the praying, waiting child of God is "strong in the Lord" (Ps 84:7; Mic 4:5; Heb 12:1).

Isaiah 40:31 Parallel Commentaries
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