"Again, you have heard that it was said to our ancestors, You must not break your oath, but you must keep your oaths to the Lord.
References for Matthew 5:33
But I tell you, don't take an oath at all: either by heaven, because it is God's throne;
or by the earth, because it is His footstool; or by Jerusalem, because it is the city of the great King.
Neither should you swear by your head, because you cannot make a single hair white or black.
But let your word 'yes' be 'yes,' and your 'no' be 'no.' Anything more than this is from the evil one.
References for Matthew 5:37