And the lintels of the posts were moved. This noise was an indication that it was not a human voice which the Prophet had heard; for no mortal man has a voice so powerful as to be capable of making the lintels and posts shake. Now, the Lord intended not only to establish the authority of his voice over the Prophet, but to confirm it to posterity in all ages, that it might never be forgotten. Let us, therefore, know that this noise confirms at this day the voice of God, that we may tremble whenever he speaks; for if inanimate and dumb creatures are moved, what ought we to do, who feel, smell, taste, and understand, for no other purpose than that we may obey his word in a holy and reverent manner? And the house was filled with smoke. This was the common and ordinary sign which the Lord employed with his ancient people; for we read that, whenever Moses entered into the tabernacle, smoke was wont to be diffused through it in such a manner that the people could not see either Moses or the tabernacle. (Exodus 33:9.) The smoke, therefore, which Isaiah describes was not an unusual occurrence; but in the ordinary way God intended to demonstrate that he would display his power in executing judgment on the people. But it may be asked, Why did God manifest his presence by this sign rather than by any other? This question may be answered in two ways. First, it was always the will of God to repress the insolence of men, in pushing their inquiries about his majesty beyond what is proper; for on this point almost all men are too rash and daring. They wish to rise above the clouds, and to penetrate into the secrets of God, while they do not see what lies at their feet. Hence arises a labyrinth of errors, and when the minds of men have been entangled in it, they adopt false and pretended modes of worship; for when men allow themselves to adopt any false notions about God, there is nothing which they will not venture to attempt against him. It was not without good reason, therefore, that he made use of smoke, in order to remind men of their weakness; and yet he did not intend that they should be blind or stupid, that is, that they should have the stupidity and error which the papists disguise under the name of simplicity; but he forbids us to inquire or search beyond what he has revealed to us in his word; for, as Augustine says, "that is a learned ignorance." Whenever, therefore, smoke of this kind is mentioned, let us know that it lays a restraint upon us from indulging curiosity in our researches into the purpose of God. Secondly, this smoke ought to strike terror, as David, when describing an angry and terrible God, says that clouds and darkness are round about him. (Psalm 97:2.) This also agrees well with the present passage; for he pronounces a dreadful judgment, namely, the blinding of the Jews. Others think that it indicated the burning by which he consumed the temple; but the view which I have given is more probable.

And the posts of the door - Margin, 'Thresholds.' There is some difficulty in the Hebrew here, but the meaning of the expression is sufficiently apparent. It means that there was a tremour, or concussion, as if by awe, or by the sound attending the cry. It is evidently a poetic expression.
The house - The temple.
Was filled with smoke - There is here, doubtless, a reference to "the cloud" that is so often mentioned in the Old Testament as the visible symbol of the Divinity; see the note at Isaiah 4:5. A similar appearance is recorded when Solomon dedicated the temple; 1-Kings 8:10; 2-Chronicles 5:13; Ezekiel 10:4.

And the posts of the door (k) moved at the voice of him that cried, and the house was filled with smoke.
(k) Which was to confirm the prophet, that it was not the voice of man: and by the smoke was signified the blindness that would come on the Jews.

And the posts of the door moved at the voice of him that cried,.... That is, the posts of the door of the temple, as the Targum adds, where this vision was seen, as represented to the prophet. Some think this respects the earthquake in Uzziah's time, mentioned in Zac 14:5 and which they suppose was at the time he attempted to offer incense, and was smitten with leprosy; but, as Kimchi observes, this moving of the door posts was only in the vision of prophecy, and not in reality; this shaking therefore may denote either the shaking and removing of the temple service and worship, at the death of Christ, and through the preaching of the Gospel; or rather the shaking of the consciences of men by the word, which made them cry out, what shall we do to be saved?
And the house was filled with smoke; this was a token either of the burning of the temple, or of the anger of God against the Jews, Psalm 18:8 or of their superstition and will worship, the cause of it, Revelation 9:1 or of the judicial blindness and darkness they were given up unto, Isaiah 6:9 or rather of the presence of God in his church, and with his ministers, Exodus 40:3 the allusion may be to the cloud of incense that covered the mercy seat, on the day of atonement, Leviticus 16:13 the passage is cited on this account in the Talmud (n).
(n) T. Bab. Yoma, fol. 53. 1.

posts of . . . door--rather, foundations of the thresholds.
house--temple.
smoke--the Shekinah cloud (1-Kings 8:10; Ezekiel 10:4).

When Isaiah heard this, he stood entranced at the farthest possible distance from Him that sat upon the throne, namely, under the door of the heavenly palace or temple. What he still further felt and saw, he proceeds to relate in Isaiah 6:4 : "And the foundations of the thresholds shook with the voice of them that cried; and the house became full of smoke." By ‛ammoth hassippim, the lxx, Vulgate, Syriac, and others understand the posts of the lintels, the supporting beams of the superliminaria, which closed the doorway at the top. But as saph is only used in other places to signify the threshold and porch (limen and vestibulum), ‛ammoth hassippim must be understood here in the (perfectly appropriate) sense of "the foundations of the thresholds" (ammâh, which bears the same relation to עם, mother, as matrix to mater, is used to denote the receptive basis into which the door-steps with their plugs were inserted, like the talmudic ammetâh derēchayyâh, the frame or box of the hand-mill (Berachoth 18b), and ammath megērah, the wood-work which runs along the back of the saw and keeps it firmly extended (Kelim 21, 3); compare the "Schraubenmutter," literally screw-mother, or female screw, which receives and holds the cylindrical screw). Every time that the choir of seraphim (הקּורא: compare such collective singulars as hâ'oreb, the ambush, in Joshua 8:19; hechâlutz, of men of war, in Joshua 6:7, etc.) began their song, the support of the threshold of the porch in which Isaiah was standing trembled. The building was seized with reverential awe throughout its whole extent, and in its deepest foundations: for in the blessed state beyond, nothing stands immoveable or unsusceptible in relation to the spirits there; but all things form, as it were, the accidentia of their free personality, yielding to their impressions, and voluntarily following them in all their emotions. The house was also "filled with smoke." Many compare this with the similar occurrence in connection with the dedication of Solomon's temple (1-Kings 8:10); but Drechsler is correct in stating that the two cases are not parallel, for there God simply attested His own presence by the cloud of smoke behind which He concealed Himself, whereas here there was no need of any such self-attestation. Moreover, in this instance God does not dwell in the cloud and thick darkness, whilst the smoke is represented as the effect of the songs of praise in which the seraphim have joined, and not of the presence of God. The smoke arose from the altar of incense mentioned in Isaiah 6:6. But when Drechsler says that it was the prayers of saints (as in Revelation 5:8; Revelation 8:3-4), which ascended to the Lord in the smoke, this is a thought which is quite out of place here. The smoke was the immediate consequence of the seraphs' song of praise.
This begins to throw a light upon the name seraphim, which may help us to decipher it. The name cannot possibly be connected with sârâph, a snake (Sanscr. sarpa, Lat. serpens); and to trace the word to a verb sâraph in the sense of the Arabic 'sarafa ('sarufa), to tower high, to be exalted, or highly honoured (as Gesenius, Hengstenberg, Hofmann, and others have done), yields a sense which does not very strongly commend itself. On the other hand, to follow Knobel, who reads shârâthim (worshippers of God), and thus presents the Lexicon with a new word, and to pronounce the word serpahim a copyist's error, would be a rash concession to the heaven-storming omnipotence which is supposed to reside in the ink of a German scholar. It is hardly admissible, however, to interpret the name as signifying directly spirits of light or fire, since the true meaning of sâraph is not urere (to burn), but Comburere (to set on fire or burn up). Umbreit endeavours to do justice to this transitive meaning by adopting the explanation "fiery beings," by which all earthly corruption is opposed and destroyed. The vision itself, however, appears to point to a much more distinctive and special meaning in the name, which only occurs in this passage of Isaiah. We shall have more to say upon this point presently.

The posts - Together with the door itself. Such violent motions were commonly tokens of God's anger. Smoak - Which elsewhere is a token of God's presence and acceptance, but here of his anger.