The reaction of some of the leading people in Jerusalem to Lehi’s message may seem to us like an overreaction. Why were they going to kill him? Was that justifiable? Actually, in Deuteronomy 18, there is a law against false prophecy, and the punishment is death. Urijah, Jeremiah and others ran into this problem. When Lehi was called to deliver essentially the same message that had gotten others in trouble, one can easily imagine Lehi thinking, "Wait a minute, Lord, haven’t we tried this already? And it didn’t work out too well last time." But, of course, he went and did it as he was commanded. And then, of course, in a dream, he was told that it was time for him to take his family and depart (2 Nephi 2:2). He woke up in the middle of the night, packed up his family, and was gone.
But where would he go? Lehi needed to flee. He may have wanted to go to Egypt, being familiar with the language and customs there. But he knew what happened with Urijah’s extrication. He was not going to go there and have that happen to him. Of course, Lehi would not have wanted to go to Babylon, because Babylon had just conquered Jerusalem, so that would have been going into enemy territory. So, what was left? Only heading south, to the Red Sea and from there on down the frankincense route.
Aston, Warren P. "Into Arabia: Lehi and Sariah’s Escape from Jerusalem." BYU Studies Quarterly 58, no. 4 (2019): 99–126.