וּמָשַׁחְתָּ֛ אֶת־מִזְבַּ֥ח הָעֹלָ֖ה וְאֶת־כָּל־כֵּלָ֑יו וְקִדַּשְׁתָּ֙ אֶת־הַמִּזְבֵּ֔חַ וְהָיָ֥ה הַמִּזְבֵּ֖חַ קֹ֥דֶשׁ קָֽדָשִֽׁים׃
At papahiran mo ng langis ang altar ng handog na susunugin at ang lahat ng kagamitan nito, at pababanalin mo ang altar, at ang altar ay magiging kabanal-banalan.
Siftei Chakhamim
I do not know... The Ramban [suggests that the source of this command is] because it says regarding the altar (Shemos 40:10): “[Sanctify the altar] so that the altar becomes holy of holies,” which indicates that additional sanctification and sprinkling was necessary, more than [the sanctification] for the other vessels. But it appears to me it is because the altar was not like the other vessels of the Mishkan, in that the hollow of the altar was filled with earth and the anointing was for the copper [exterior] alone. However, there was no anointing for the earth that filled its hollow space. Therefore, he sprinkled unto the altar in the place where they were bringing sacrifices after it was filled with earth. It needed anointing because it was no less than other vessels (Gur Aryeh).