Jeremiah 51:12

Set up the standard upon the walls of Babylon,.... This is not said to the Medes and Persians, to put up a flag on the walls of Babylon, as a sign of victory, as Kimchi, Abarbinel, and others think; for as yet the city is not supposed to be taken by what follows; but rather to the Babylonians, to set up an ensign on their walls, to gather the inhabitants together, to defend their city, and the bulwarks of it; which, with what follows, is ironically spoken:make the watch strong; to guard the city; observe the motions of the enemy, and give proper and timely notice; increase and double it:set up watchmen; meaning the keepers of the walls; place them upon them, to keep a good look out, that they might not be surprised: this seems to respect the great carelessness and security the whole city was in the night it was taken; being wholly engaged in feasting and revelling, in rioting and drunkenness, having no fear of danger, or concern for their safety; with which they are tacitly upbraided:prepare the ambushes; or, "liers in wait" ; to second or relieve those on the walls upon occasion; or seize unawares the besiegers, should they attempt to scale the walls, and enter the city:for the Lord hath devised and done that which he spoke against the inhabitants of Babylon; or as he hath devised, so hath he done, or will do: his purposes cannot be frustrated, his counsel shall stand; and therefore had the Babylonians been ever so industrious in their own defence, they could never have prevented their ruin and destruction, which was resolved upon, and accordingly effected.