Alma 50:21

And we see that these promises have been verified to the people of Nephi; for it has been their quarrellings, and their contentions; yea, their murderings, and their plunderings, their idolatry, their whoredoms, and their abominations, which were among themselves, which brought upon them their wars and their destructions.

We can see that these promises came true for the Nephites. It was their fighting and arguing that hurt them. It was their killing and stealing. It was when they worshiped idols and did bad things. These things brought wars and trouble.

We can see these promises coming true among the Nephites. Their own quarrels and fights—their murders, robberies, idol worship, sexual sin, and other terrible things among themselves—these brought war and destruction on them.