Leviticus 8:15

ויחטא את המזבח AND HE PURIFIED THE ALTAR — He cleansed and purified it from anything “strange” (alien to the sacred purpose for which the altar was intended) that may have happened to it, so that it might enter into a state of holiness (cf. Rashi on Exodus 19:36). ויקדשהו AND HE SANCTIFIED IT by this rite. לכפר עליו THAT ONE MIGHT MAKE EXPIATION UPON IT from that time onward with all atonement sacrifices (i. e. that all atonement sacrifices might henceforth be offered upon it; the meaning is not that he sanctified it so that he might now offer an atonement offering for it or upon it).

וַיִּשְׁחָ֗ט וַיִּקַּ֨ח מֹשֶׁ֤ה אֶת־הַדָּם֙ וַ֠יִּתֵּ֠ן עַל־קַרְנ֨וֹת הַמִּזְבֵּ֤חַ סָבִיב֙ בְּאֶצְבָּע֔וֹ וַיְחַטֵּ֖א אֶת־הַמִּזְבֵּ֑חַ וְאֶת־הַדָּ֗ם יָצַק֙ אֶל־יְס֣וֹד הַמִּזְבֵּ֔חַ וַֽיְקַדְּשֵׁ֖הוּ לְכַפֵּ֥ר עָלָֽיו׃

And he slaughtered it; and Moshe took the blood, and put it upon the horns of the altar round about with his finger, and purified the altar, and poured the blood at the bottom of the altar, and sanctified it, to make atonement upon it.