John Gill Commentary Jeremiah 48:40

"For thus saith Jehovah: Behold, he shall fly as an eagle, and shall spread out his wings against Moab." — Jeremiah 48:40 (ASV)

For thus says the Lord, behold, he shall fly as an eagle, &c.] The enemy, Nebuchadnezzar king of Babylon, with his army; who is compared to an eagle for his strength, swiftness, and greediness after the prey: and shall spread his wings over Moab; as an eagle spreads its wings, which are very large, over the little birds it seizes upon as its prey; so the king of Babylon would bring a numerous army against Moab, and spread it over his country. The Targum is, ``behold, as all eagle which flies, so a king shall come up with his army, and encamp against Moab.''