Leviticus 14:18

18 The rest of the oil in his palm the priest shall put on the head of the one to be cleansed and make atonement for them before the LORD.

Read Leviticus 14:18 Using Other Translations

And the remnant of the oil that is in the priest's hand he shall pour upon the head of him that is to be cleansed: and the priest shall make an atonement for him before the LORD.
And the rest of the oil that is in the priest's hand he shall put on the head of him who is to be cleansed. Then the priest shall make atonement for him before the LORD.
The priest will apply the oil remaining in his hand to the head of the person being purified. Through this process, the priest will purify the person before the LORD .