Leviticus 8:15

8:15 and he slaughtered it. Moses then took the blood and put it all around on the horns of the altar with his finger and decontaminated the altar, and he poured out the rest of the blood at the base of the altar and so consecrated it to make atonement on it.

Leviticus 9:9

9:9 Then Aaron’s sons presented the blood to him and he dipped his finger in the blood and put it on the horns of the altar, and the rest of the blood he poured out at the base of the altar.