# is required to swear

This can be stated in active form. AT: "someone requires him to swear" (See: [[rc://en/ta/man/translate/figs-activepassive]])

# upon his own head

Here "head" refers to the whole person. AT: "on him" (See: [[rc://en/ta/man/translate/figs-synecdoche]])

# give to him according to his righteousness

"to give him what he deserves because he is righteous"