Him that dwelleth therein - That is, God. The temple was his house, his dwelling. In the first, or Solomon's temple, he dwelt between the cherubims in the most holy place. He manifested himself there by a visible symbol, in the form of a cloud resting on the mercy-seat, 1-Kings 8:10, 1-Kings 8:13; Psalm 80:1.

Whoso shall swear by the temple - Perhaps it is to this custom of swearing by the temple, that Martial alludes, lib. xi. epist. 95.
Ecce negas, jurasque mihi per templa Tonantis; Non credo; jura, Verpe, per Anchialum.
"Behold, thou deniest, and swearest to me by the temples of Jupiter; I will not credit thee: swear, O Jew, by the temple of Jehovah."
This word probably comes from היכל יה heical Yah, the temple of Jehovah. This seems a better derivation than אם חי אלהים im chai Elohim, as God liveth, though the sound of the latter is nearer to the Latin.
By him that dwelleth therein - The common reading is κατοικουντι, dwelleth or Inhabiteth, but κατοικησαντι, dwelt or Did inhabit, is the reading of CDEFGHKLM, eighty-six others; this reading has been adopted in the editions of Complutum, Colineus, Bengel, and Griesbach. The importance of this reading may be perceived by the following considerations. In the first Jewish temple, God had graciously condescended to manifest himself - he is constantly represented as dwelling between the cherubim, the two figures that stood at each end of the ark of the covenant; between whom, on the mercy seat, the lid of the ark, a splendor of glory was exhibited, which was the symbol and proof of the Divine presence. This the Jews called שכינה Shekinah, the habitation of Jehovah. Now the Jews unanimously acknowledge that five things were wanting in the second temple, which were found in the first, viz.,
1. The ark;
2. The holy spirit of prophecy;
3. The Urim and Thummim;
4. The sacred fire; and
5. The שכינה Shekinah.
As the Lord had long before this time abandoned the Jewish temple, and had now made the human nature of Jesus the Shekinah, (see John 1:14, the Logos was made flesh, εσκηνωσεν, and made his tabernacle - made the Shekinah, - among us), our Lord could not, with any propriety, say that the supreme Being did now inhabit the temple; and therefore used a word that hinted to them that God had forsaken their temple, and consequently the whole of that service which was performed in it, and had now opened the new and living way to the holiest by the Messiah. But all this was common swearing; and, whether the subject was true or false, the oath was unlawful. A common swearer is worthy of no credit, when, even in the most solemn manner he takes an oath before a magistrate; he is so accustomed to stake his truth, perhaps even his soul, to things whether true or false, that an oath cannot bind him, and indeed is as little respected by himself as it is by his neighbor. Common swearing, and the shocking frequency and multiplication of oaths in civil cases, have destroyed all respect for an oath; so that men seldom feel themselves bound by it; and thus it is useless in many cases to require it as a confirmation, in order to end strife or ascertain truth. See the note on Matthew 5:37.

And whoso shall swear by the temple,.... As we have before seen they used to do, and as appears from what the poet says (w):
Ecce negas, jurasque mihi per templa tonantis Non credo: jura, verpe, per Anchialum.
In which he intimates, that if the Jew swore by the temple, he would not believe him; as well he might not, since such an oath was accounted nothing; but bids him swear by Anchialus, that is, by "Chi Eloah", or , "Chi Alon", or "Elion, the living God", or , "Chi Haolam, he that lives for ever" (x); and suggests, that he should then believe him. Now our Lord, though he did not allow of such swearing, yet justly argues, that he that sweareth by the temple, not only "sweareth by it", which could not be a witness of what was swore; but he must be interpreted to swear by the inhabitant of it, and by him that dwelleth in it; that is, God, for whom it was built, to whom it was dedicated; where he was worshipped, and where he vouchsafed to reside; taking up his dwelling between the cherubim upon the mercy seat, in the most holy place; from whence he communed with men, and gave tokens of his presence; and who only could be the proper witness of the truth, or falsehood, of what was swore; and therefore an oath, by the temple, ought to be looked upon as if made by God himself, and so to be sacred and binding.
(w) Martial. Epigr. l. 11. Ep. 60. (x) Vid. Selden. Prolegomena ad lib. de Successionibus.

By the temple. Oaths that did they not call binding, Jesus traces to God himself. Compare Matthew 5:35. The meaning is that all oaths are by God. There are no distinctions.