Charles Ellicott Commentary 1 Kings 1:50

"And Adonijah feared because of Solomon; and he arose, and went, and caught hold on the horns of the altar." — 1 Kings 1:50 (ASV)

The horns of the altar. The horns were projections from the altar, to which the victims were fastened, and on which the blood was sprinkled (Exodus 29:12). To take hold of them was, of course, to claim the right of sanctuary—a right, however, that the Law, ruled as usual by moral considerations, formally denied to willful murder (Exodus 21:14), and which accordingly (see 1 Kings 2:30–31) was later refused to Joab. Adonijah, by the acknowledgment of “King Solomon,” seems to represent his usurpation as one of those acts of haste and inadvertency, to which alone sanctuary was conceded.