2 Bible Verses about Covenant Obligations

Again, you have heard that to our ancestors it was said--'Thou shalt not break an oath, but thou shall keep thine oaths as a debt due to the Lord.' I, however, say to you that you must not swear at all, either by Heaven, since that is God's throne, Or by the earth, since that is his footstool, or by Jerusalem, since that is the city of the Great King.read more.
Nor should you swear by your head, since you cannot make a single hair either white or black. Let your words be simply 'Yes' or 'No'; anything beyond this comes from what is wrong.

To take an illustration, Brothers, from daily life--No one sets aside even an agreement between two men, when once it has been confirmed, nor does he add conditions to it.