Christian apologists argued monogamy from scripture’s singular wording.

Evidence

The argument, at once rational and Scriptural, una dicitur esse unius, appears with Alan of Lille. Alan’s arguments were idiosyncratic because of his mistaken assumption that Muslims argued from the Old Testament, in the text known to Christians. The patriarchs, he said, had been licensed, that the earth might be replenished, but now it was chastity that was needed, in order to replenish Heaven. The Gregorian Report used Scripture traditionally, but with some humour: ‘according to Genesis, they shall be two in one flesh; it does not say, three or four’. — Norman Daniel, Islam and the West, 809

Categorization

• CANDY: ‘It does not say, three or four’ is a genuinely funny medieval one-liner worth quoting in conversation.
• XREF: The ‘two in one flesh; it does not say three or four’ quip and the patriarchs-licensed-for-replenishment argument echo the same proof-texting style of today’s Biblical inerrancy debates.