What did Qayin (Cain) tell his brother Hevel (Abel) before they went out into the field?

Answer From The Annual Reading Schedule - Week 1 Notes For Genesis: The answer is not found in the Hebrew Masoretic scrolls. To find the answer, we turn to Brenton's English translation of the Greek Septuagint. The Septuagint, although Greek, may provide useful information in situations where the English translation is relying primarily on the Masoretic Hebrew scrolls which only dates back to 1,000 AD. The Greek Septuagint, on the other hand, dates back to approximately at or before the time the Mashiach (Christ) Yahushua came. Brenton's 1851 English translation of the Greek Septuagint shows that Qayin (Cain) said, "Let us go out into the plain".