Charles Ellicott Commentary Genesis 15:5

"And he brought him forth abroad, and said, Look now toward heaven, and number the stars, if thou be able to number them: and he said unto him, So shall thy seed be." — Genesis 15:5 (ASV)

He brought him forth. —There is no reason for regarding this as a poetical description of a merely mental emotion. With his senses dormant, but alive to every spiritual impression, Abram feels himself led forth from the tent into the open space around, and is there commanded to count the stars. As a matter of fact, the stars visible to the naked eye are not very numerous, but they have always been a received metaphor for an infinite multitude, probably because, as people gaze, they perpetually see the faint radiance of more and more distant constellations. Thus they cannot be counted, and Abram’s seed was to be countless, because of the vastness of its number.