NKJV:

Marriage is Sacred

31 Furthermore it has been said, 'Whoever divorces his wife, let him give her a certificate of divorce' 

32 But I say to you that whoever divorces his wife for any reason except sexual immorality causes her to commit adultery; whoever marries a women who is divorced commits adultery.

Jesus Forbids Oaths 

33 Again you have heard it was said to those of old 'You shall not swear falsely, but shall perform your oaths to the Lord'

34 But I say to you, do not swear at all; neither by heaven, for it is God's throne

35 Nor by the earth, it is God's footstool; nor by Jerusalem, for it is the city of the great King

36 Nor shall you swear by your head, because you cannot make one hair white or black

37 But let your yes be yes and no, no. For whatever is more than these is from the evil one.