John Gill Commentary Nahum 3:7

"And it shall come to pass, that all they that look upon thee shall flee from thee, and say, Nineveh is laid waste: who will bemoan her? whence shall I seek comforters for thee?" — Nahum 3:7 (ASV)

And it shall come to pass, [that] all they that look upon you
shall flee from you
As something loathsome and abominable, not fit to be come near unto, or touched; and as astonished and amazed at an object so forlorn and miserable, and lest they should partake of the same punishment:

and say, Nineveh is laid waste;
utterly destroyed; its walls broke down, its houses demolished, its substance plundered, and its inhabitants killed, or carried captive; who could have thought it, when it was once so stately, rich, and powerful? but so it is indeed!

who will bemoan her?
there are none left in her to do it; and as for others, her neighbours, whom she has oppressed and cruelly used, these will laugh and rejoice, instead of lamenting her case:

From where shall I seek comforters for you?
none from among her inhabitants, being destroyed, or carried into a foreign land; and none from among the nations round about, who will rather deride and insult than pity and comfort; so wretched and miserable would her case be!