Matthew 5:35
Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King.
Nor by the earth, for it is his footstool,.... That the Jews were wont to swear by the earth, is clear from the above mentioned instances; and is condemned by Christ for this reason, because the earth is God's "footstool", referring, as before, to Isaiah 66:1 on which he treads; and where he also manifests forth his glory, and is a considerable part of the work of his hands.
neither by Jerusalem, which the Jews used to swear by: such forms of vows as these are to be met with in their writings {q};
"as the altar, as the temple, Mlvwryk, "as Jerusalem";''
that is, by Jerusalem, I vow I will do this, or the other thing.
"R. Judah says, he that says Jerusalem (i.e. as Bartenora observes {r}, without the note of comparison, as) says nothing.''
In the Gemara {s} it is,
"he that says as Jerusalem, does not say anything, till he has made his vow concerning a thing, which is offered up in Jerusalem.''
Dr. Lightfoot {t} has produced forms of vowing and swearing, which have not occurred to me.
"Jerusalem; Mlvwryl, "for", or "unto Jerusalem", which exactly answers to eiv Ierosoluma, here; and "by Jerusalem";''
The reason given for prohibiting this kind of oath, is;
for it is the city of the great king: not of David, but of the King of kings, the Lord of hosts; who had his residence, and his worship, here; see Psalms 48:2.
{q} Misn. Nedarim, c. 1. sect. 3.
{r} In. ib.
{s} T. Bab. Nedarim, fol. 11. 1.
{t} In loc. ex Tosapht. in Nedarim, c. 1.