But Nineveh is of old like a pool of water: yet they shall flee away. Stand, stand, shall they cry; but none shall look back.
But - rather, 'though' (G.V. Smith).
Is of old - rather, from the days that she hath been, from the earliest period of her existence. Alluding to Nineveh's antiquity (Genesis 10:11).
Yet they shall flee away. 'Though Nineveh has been of old defended by water surrounding her, yet her inhabitants shall flee away.' Grotius, less probably (cf. Nahum 3:8-12), interprets, the 'waters' of her numerous population (Isaiah 8:7; Jeremiah 51:13; Revelation 17:15).
Stand, stand, shall they cry; but none shall look back - i:e., the few patriotic citizens shall cry to their fleeing countrymen; 'but none looketh back,' much less stops in flight, so panic-stricken are they.