Isaiah 40:5

“And the glory of the Lord shall be revealed. &c.] Christ himself, who is the brightness of his Father’s glory, and his own glory, as the glory of the of the only begotten of the Father; the glorious perfections of his nature, seen in the miracles wrought, and in the doctrines taught by him; the glory of the divine Father, in the face or person of Christ; and the glory of his attributes, in the work of salvation by him; all which is most clearly discerned in the glass of the Gospel, or in the ministry of the word, by John, Christ himself, and his apostles: and all flesh shall see it together; not the Jews only, but Gentiles also; not with their bodily eyes, but with the eyes of their…”

“see it--The Septuagint for "it," has "the salvation of God." So Luk 3:6 (compare Luk 2:30, that is, Messiah); but the Evangelist probably took these words from Isa 52:10. for--rather, "All flesh shall see that the mouth of Jehovah hath spoken it" [BENGEL].”

“And the glory of the Lord - The phrase here means evidently the majesty, power, or honor of Yahweh. He would display his power, and show himself to be a covenant-keeping God, by delivering his people from their bondage, and reconducting them to their own land. This glory and faithfulness would be shown in his delivering them from their captivity in Babylon; and it would be still more illustriously shown in his sending the Messiah to accomplish the deliverance of his people in later days. And all flesh - All human beings. The word ‘flesh’ is often used to denote human nature, or mankind in general Genesis 6:12; Psalms 65:3; Psalms 145:21. The idea is, that the deliverance of his people would…”

“40:5 The future revelation of God’s glory would include the return of Judah from exile but would also go beyond it. The New Testament confirmed that the revelation of God’s glory came in Jesus Christ (John 1:14; Heb 1:3). • The Lord has spoken: The coming salvation and judgment would certainly occur because the Lord, who keeps his word, had declared it (see Isa 1:20; 58:14).”

“the glory: Isa 6:3, Isa 11:9, Isa 35:2, Isa 60:1; Psa 72:19, Psa 96:6, Psa 102:16; Hab 2:14; Luk 2:10-14; Joh 1:14, Joh 12:41; Co2 3:18, Co2 4:6; Heb 1:3; Rev 21:23 all flesh: Isa 49:6, Isa 52:10, Isa 66:16, Isa 66:23; Jer 32:27; Joe 2:28; Zac 2:13; Luk 2:32, Luk 3:6; Joh 17:2; Act 2:17 for the mouth: Isa 1:20, Isa 58:14; Jer 9:12; Mic 4:4 Isaiah 40:6”

“The cry of the crier proceeds thus in Isa 40:5 : "And the glory of Jehovah will be revealed, and all flesh seeth together: for the mouth of Jehovah hath spoken it." The pret. cons. קנגלה is here apodosis imper. When the way is prepared for Jehovah the Coming One, the glory of the God of salvation will unveil itself (on the name Jehovah, which is applied to God, the absolute I, as living and revealing Himself in history, more especially in the history of salvation). His parousia is the revelation of His glory ( Pe1 4:13). This revelation is made for the good of Israel, but not secretly or exclusively; for all the human race, called here designedly "all flesh" (kol bâsâr), will come to see…”