A scripture on oathtaking:
Again, you have heard that it was said to the people long ago, “Do not break your oath, but keep the oaths you have made to the Lord.” But I tell you, Do not swear at all: either by heaven, for it is God’s throne; or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. (Matthew 5:33-35)
From Article 20 of the Confession of Faith from a Mennonite Perspective:
We commit ourselves to tell the truth, to give a simple yes or no, and to avoid swearing of oaths.