1 Nephi 21: 17

17 Thy children shall make haste against thy destroyers; and they that made thee waste shall go forth of thee.

Although, as stated in the last few verses, the Lord will not forget or forsake Israel, He won’t deliver them from their hardships and persecutions right away either. This verse is a promise to future generations of Israel. Eventually Israel will win over their enemies, but not the generation that Isaiah is addressing. That generation had not earned the kind of deliverance that is promised here. So although the Lord would remember and honor His covenants to Israel, there’s no promise on the timing, except here. And this just reveals that it would be in the future some time (“thy children” would do these things). Those who caused the problems would “go forth of [Israel],” or in other words, leave them, or even be chased out by Israel. Or it also refers to the persecutors fleeing Israel. Either way, the problem will be resolved.