John Gills Exposition of the Bible Commentary - Genesis 15:12
And when the sun was going down ,.... Just setting, descending below the hemisphere; or "about to enter" F13 ויהי השמש לבוא "et fuit sol ad intrandum", Montanus, Piscator. into his chamber, as Piscator observes, from whence he went forth in the morning, as a strong man to run his race; which at sunset is finished according to human appearance, and the common apprehensions of men, who have thought it goes under the earth, or drops into the ocean, see Psalm 19:5 , a deep sleep... read more
Matthew Henry's Complete Commentary - Genesis 15:12-16
We have here a full and particular discovery made to Abram of God's purposes concerning his seed. Observe, I. The time when God came to him with this discovery: When the sun was going down, or declining, about the time of the evening oblation, 1 Kgs. 18:36; Dan. 9:21. Early in the morning, before day, while the stars were yet to be seen, God had given him orders concerning the sacrifices (Gen. 15:5), and we may suppose it was, at least, his morning's work to prepare them and set them in order;... read more