From the early Church Fathers to now.
“Stood behind, between the Egyptians’ camp and the camp of Israel: and it was a dark cloud, and enlightening the night, so that they could not come at one another all the night.”
“Therefore this darkness of the body has been placed between us and God, like the cloud of old between the Egyptians and the Hebrews. This is perhaps what is meant by "He made darkness his separate place," namely, our dullness, through which few can see even a little.”
“And it is written also in Exodus that when the ruler of the land of the Egyptians with his warriors was pursuing after the Israelites and was already upon the point of engaging with them in battle, the angel of God stood between the camp of the Israelites and of the Egyptians, and the one came not near the other all the night. There is therefore nothing unbefitting in supposing here also that the holy angel who was the guardian of the synagogue offered supplications in its behalf and prayed for a respite, if perchance yielding to better influence it might yet bring forth fruit.”
The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.