Wo is me! - That is, I am filled with overwhelming convictions of my own unworthiness, with alarm that I have seen Yahweh.
For I am undone - Margin, ‘Cut off.’ Chaldee, ‘I have sinned.’ Septuagint, ‘I am miserable, I am pierced through.’ Syriac, ‘I am struck dumb.’ The Hebrew word may sometimes have this meaning, but it also means “to be destroyed, to be ruined, to perish;” see Hosea 10:15; Zephaniah 1:2; Hosea 4:6; Isaiah 15:1. This is probably the meaning here, ‘I shall be ruined, or destroyed.’ The reason of this, he immediately states.
A man of unclean lips - This expression evidently denotes that he was a “sinner,” and especially that he was unworthy either to join in the praise of a God so holy, or to deliver a message in his name. The vision; the profound worship of the seraphim; and the attendant majesty and glory, had deeply impressed him with a sense of the holiness of God, and of his own unfitness either to join in worship so holy, or to deliver the message of so pure a God. A similar effect is recorded in reference to Abraham; Genesis 18:27; see also Exodus 4:10, Exodus 4:12; Jeremiah 1:6. A deep consciousness of guilt, in view of the holiness and majesty of God, is also described by Job:
I have heard of thee by the hearing of the ear
But now mine eye seeth thee.
Wherefore I abhor myself,
And repent in dust and ashes.
An effect also remarkably similar is described in reference to the apostle Peter, Luke 5:8 : “When Simon Peter saw it (the miracle which Jesus had performed), he fell down at Jesus’ knees, saying, ‘Depart from me, for I am a sinful man, O Lord. ‘“
A people of unclean lips - A people who are unworthy to celebrate the praises of a God so pure and exalted.
Mine eyes have seen - In Exodus 33:20, it is said: ‘Thou canst not see my face, for there shall no man see me and live;’ compare John 1:18; 1 Timothy 6:16. Perhaps it was in recollection of this, that Isaiah said he was undone. It is not, however, to be understood that the prophet saw Yahweh Himself, but only the “symbol” of His presence. It was for this expression, according to the tradition of the Jews, that Manasseh took occasion to put the prophet to death; see the Introduction, Section 2.
The Lord of hosts - Yahweh of hosts. John applies this to the Lord Jesus, and this proves that he is divine; see John 12:41.