To be sure,
some have read the Greek in Matthew 5:34 and James 5:12 as forbidding all oaths
or promises of any kind (“swear not at all,” “swear no other
oath”), but this does not capture what appears to be the historical intent of
Jesus (as reflected explicitly in Matthew 23), and these two texts can be
interpreted otherwise: I read the Greek in James 5:12 as telling Christians not
to swear ay such oath, meaning one that swears by external things, by heaven,
or by earth, or by any other such thing (allon tina). The problem lies
in bringing in “extralinguistic props” and thereby failing to swear by God
himself, who dwells in those places and sanctifies those oaths. James
admonishes his followers to let their “yes” really be a “yes” and their “no”
really be a “no,” and to keep their solemn promises literally “so that they not
fall under judgment [of the Lord].”
A rabbinic
aphorism suggest a similar sentiment in general speech: “Let your Yes and No
both be righteous. Do not speak with your mouth what you do not mean in your
heart.” But much more is at stake in the Sermon on the Mount than simply
speaking honestly one’s daily conversation. The use of a mere “yes” or “no” had
precedent in “cultic-ritual oracles” in which “a ‘token’ was either of good or
of evil omen, [and therefore] would answer either ‘yes’ or ‘no.’” Even the
Essenes, who rejected oaths in general, used “the oath at entering the sect.”
In a temple context, the Sermon on the Mount is likewise concerned with the
complete integrity of oaths made in the name of the Lord and with the full
sincerity of vows made to God in the holy place. (John W. Welch, The Sermon
on the Mount in the Light of the Temple [Society for Old Testament Study
Monographs; London: Routledge, 2009], 103-4)