Adam Clarke on Song of Solomon 2:17

Until the day break - Literally, until the day breathe; until the first dawn, which is usually accompanied with the most refreshing breezes.

The shadows flee away - Referring to the evening or setting of the sun, at which all shadows vanish.

The mountains of Bether - Translated also mountains of division, supposed to mean the mountains of Beth-horon.

There was a place called Bithron, 2Sam 2:29, on the other side of Jordan; and as the name signifies Partition, it might have had its name from the circumstance of its being divided or separated from Judea by the river Jordan.

With this chapter the second night is supposed to end.