And do not swear by your head, because you cannot make one hair white or black.
In this passage Jesus continues His previous thoughts, making it clear that people should also avoid swearing by their own head. Jesus explains that a person does not have control even over his own body, in this case, the color of his hair. Human strength is limited, and it is God who governs everything. This word once again shows that, with his limitations and weak strength, a person cannot swear even by himself, because even his influence over himself depends entirely on God. Jesus calls people to be truthful and honest in their words, without oaths, because a truthful and honest word, by its very content, does not unnecessarily involve the holy things of God.