“¶ Againe, yee haue heard that it hath beene said by them of old time, Thou shalt not forsweare thy selfe, but shalt performe vnto the Lord thine othes.”
1611 King James Version (KJV)
5:33 Our Lord here refers to the promise made to the pure in heart of seeing God in all things, and points out a false doctrine of the scribes, which arose from their not thus seeing God. What he forbids is, the swearing at all, by any creature, in our ordinary conversation: both of which the scribes and Pharisees taught to be perfectly innocent. #Exod 20:7|.
Mt 5:33 Thou shalt not forswear thyself. See Le 19:12 Nu 25:2. The Jews held that this only prohibited swearing falsely and by the name of God.