Hence the Quakers consider the common administration of oaths to have a
tendency that is injurious to the moral interests of men.

This notion relative to the bad tendency of oaths, the Quakers state to
have prevailed even in the Gentile world. As Heathen philosophy became
pure, it branded the system of swearing as pernicious to morals. It was
the practice of the Persians to give each other their right hand as a
token of their speaking the truth. He, who gave his hand deceitfully,
was accounted more detestable than if he had sworn the Scythians, in
their conference with Alexander the Great, addressed him thus: "Think
not that the Scythians confirm their friendship by an oath. They swear
by keeping their word." The Phrygians were wholly against oaths. They
neither took them themselves, nor required them of others. Among the
proverbs of the Arabs, this was a celebrated one, "Never swear, but let
thy word be yes or no." So religious was Hercules, says Plutarch, that
he never swore but once. Clinias, a Greek philosopher, and a scholar of
Pythagoras, is said to have dreaded an oath so much, that, when by
swearing he could have escaped a fine of three talents, he chose rather
to pay the money than do it, though he was to have sworn nothing but the
truth. Indeed, throughout all Greece, the system of swearing was
considered as of the most immoral tendency, the very word, which
signified "perjured," in the Greek language, meaning, when analysed, "he
that adds oath to oath," or "the taker of many oaths."

But, above all, the Quakers consider oaths as unlawful for Christians,
having been positively forbidden by Jesus Christ.

The words, in which they conceived this prohibition to have been
contained, they take from the sermon on the Mount.