For all flesh is as grass,.... All men, as born of corruptible seed, are frail, mortal, and perishing; they spring up like grass, and look beautiful for a while, but are very weak and tender, and in a little time they are cut down by death, and wither away; and while they live, are, in a good measure, nothing but grass in another form; the substance of their life is greatly by it; what is the flesh they eat, but grass turned into it?
and this mortality is not only the case of wicked men, as the Jews interpret the word, but of good men; even of the prophets, and preachers of the Gospel; and yet the word of God spoken by them continues for ever: the passage referred to is in Isa 40:6and all the glory of man as the flower of the grass; all outward things which are in esteem with men, and render them glorious to one another, as riches, honour, wisdom, strength, external righteousness, holiness, and goodness; all which are fading and transitory, like the flower of the field; but the Gospel continues, and reveals durable riches, and honour with Christ; and true wisdom and strength with him, and spiritual knowledge, in comparison of which, all things are dross and dung; and an everlasting righteousness; and true holiness in him: some have thought respect may be had to the legal dispensation, and to all the glory and stateliness and goodliness of the worship and ordinances of it, which were to endure but for a time, and are now removed; and the Gospel dispensation has taken place of them, which will continue to the end of the world:the grass withereth, and the flower thereof fadeth away; and so fading are all the above things.
Targum, Jarchi, & Kimchi, in Isa. xl.