In 1 Nephi chapter 2, Lehi takes his family out of Jerusalem because he fears for his life. He had prophesied the destruction of Jerusalem because of wickedness in the city. He was told by the Lord that he needed to leave, or else he would meet the same fate as the other prophets.
It is so true that the Lord’s people have continually killed the prophets. They killed Isaiah, Jeremiah, and many others. Of course, they didn’t kill all of them. Only those who warned them to not do the things that they were doing. Yes, several of the prophets did live long lives, but Lehi was told by the Lord that if he stayed in Jerusalem, he would not be one of them. So, they all left. They left their wealth and everything they had, except for provisions, behind.
Nephi believed his father, but his elder brothers, Laman and Lemuel, didn’t. They were caught up in the ways of the world, and didn’t believe that Jerusalem could be destroyed.
Well, history shows that Jerusalem was eventually destroyed. The city was invaded, and the inhabitants were taken prisoner, or killed. So, Lehi and his family were correct by leaving Jerusalem.
Nephi wanted to understand what his father learned, so he prayed for understanding; and he heard the Lord. The Lord told him that he would lead the people to a more prosperous land, if he continued to be true and faithful. He, the Lord, also told him that his brothers would eventually turn against him. Nephi loved his brothers, so he did not complain about them. He had faith that his father knew what he was doing. The Lord also told Nephi that if he ever was not diligent in keeping the commandments, his wicked brethren, by their example, would be a curse to him, and his children.