Lehi, who has presumably heard some of the prophets’ predictions of gloom and doom, decides to pray to the Lord on the people’s behalf. The sequence is a reliable pattern throughout the Book of Mormon: a person receives revelation only after prayer and earnest inquiry. God in the Book of Mormon doesn’t typically impart visions or insights out of the blue; he responds to their heartfelt prayers. Here, Lehi prays and has a vision that confirms the fate of Jerusalem should people fail to repent.