Exodus 27:2

And thou shalt make the horns of it upon the four corners thereof, hornlike projections which were firmly attached to the altar, as though growing out of it. They are often mentioned, and their significance appears from the fact that the blood of the sin-offering was put upon them, and that people fleeing for their life took hold of them for their protection, Leviticus 4:7; 1 Kings 1:50. His horns shall be of the same, that is, made of acacia wood, like the body of the altar; and thou shalt overlay it with brass.