John 8:3

In adultery] The woman was only betrothed, not married, otherwise her punishment would not have been stoning, but strangulation, for so the rabbis interpreted Leviticus 20:10; Deuteronomy 22:22. But inasmuch as among the Jews betrothal was almost equivalent to marriage (see on Matthew 1:18), the sin of a betrothed woman was regarded as a species of adultery.