1 Kings 1:51
And it was told Solomon, saying, Behold, Adonijah feareth king Solomon: for, lo, he hath caught hold on the horns of the altar, saying, Let king Solomon swear unto me to day that he will not slay his servant with the sword. And it was told Solomon, saying, Behold, Adonijah feareth king Solomon: for, lo, he hath caught hold on the horns of the altar, saying, Let king Solomon swear unto me to day that he will not slay his servant with the sword.
Adonijah fled to the altar after his failed attempt to seize the throne from David, fearing that Solomon would have him executed for his rebellion. He laid hold on the horns of the altar as a plea for protection, asking that the new king swear to him that day that he would not put his servant to death with the sword. His appeal sought mercy and a sparing of his life, yet it did not erase the guilt of his rebellion. He was spared for a time, but his crime remained upon him and he was later executed.