Matthew 5:34-36
From Wesleyan Discipline
5:34 But I tell you, do not swear an oath at all: either by heaven, for it is God’s throne; 5:35 or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. 5:36 And do not swear by your head, for you cannot make even one hair white or black.