Matthew 5:35

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 F17 Misn. Nedarim, c. 1. sect. 3. ;

"as the altar, as the temple, כירושלם , "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 F18 In. ib. , without the note of comparison, as) says nothing.'

In the Gemara F19 T. Bab. Nedarim, fol. 11. 1. 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 F20 In loc. ex Tosapht. in Nedarim, c. 1. has produced forms of vowing and swearing, which have not occurred to me.

"Jerusalem; לירושלם , "for", or "unto Jerusalem", which exactly answers to εις Ιεροσολυμα , 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 Psalm 48:2 .