1 Kings 1:50

And Adonijah feared because of Solomon, and arose, and went, and caught hold on the horns of the altar.

Adonijah made a bid to take the throne for himself in place of Solomon, whom God had appointed to be king. His attempt failed, and in fear of Solomon he fled and took hold of the horns of the altar to seek mercy. Solomon spared his life at that time despite the rebellion. After the death of David, however, Adonijah faced and suffered the penalty for his rebellious course.