en_tn/2sa/02/27.md

Just as God lives

This is a very strong vow. Alternate translation: "With God as my witness" or "God will affirm that I mean what I say"

if you had not said that ... pursued their brothers until the morning

Joab spoke about what did not happen to show how good it was that Abner said what he said. Because Abner said what he said, Joab would tell his soldiers to stop chasing their brothers. (See: rc://en/ta/man/jit/figs-hypo)