Charles H. Spurgeon on Psalms 118:27

Even unto the horns of the altar. Before these words must be understood, lead it: for the victims were bound to rings fixed in the floor. "The horns" were architectural ornaments, a kind of capitals, made of iron or of brass, somewhat in the form of the curved horns of an animal, projecting from the four angles of the altar. The officiating priest, when he prayed, placed his hands on them, and sometimes sprinkled them with the blood of the sacrifice: compare Ex 30:3 Le 4:7,18. At the end of this verse the word saying must be supplied. Daniel Cresswell.