sling out - expressing the violence and suddenness of the removal to Babylon. A similar image occurs in Jer 16:13; 1Sa 25:29; Isa 22:17, Isa 22:18.
at this once - at this time, now.
find it so - find it by experience, that is, feel it (Eze 6:10). Michaelis translates, “I will bind them together (as in a sling) that they may reach the goal” (Babylon). English Version is best: “that they may find it so as I have said” (Num 23:19; Eze 6:10).