And the priest shall take some of the log of oil, and pour it into the palm of his own left hand:

Wesley's Notes

14:15 The oil - As the blood signified Christ's blood by which men obtained remission of sins, so the oil noted the graces of the spirit by which they are renewed.

Matthew Henry's Concise Commentary

14:10-32 The cleansed leper was to be presented to the Lord, with his offerings. When God has restored us to enjoy public worship again, after sickness, distance, or otherwise, we should testify our thanksgiving by our diligent use of the liberty. And both we and our offerings must be presented before the Lord, by the Priest that made us clean, even our Lord Jesus. Beside the usual rites of the trespass-offering, some of the blood, and some of the oil, was to be put upon him that was to be cleansed. Wherever the blood of Christ is applied for justification, the oil of the Spirit is applied for sanctification; these two cannot be separated. We have here the gracious provision the law made for poor lepers. The poor are as welcome to God's altar as the rich. But though a meaner sacrifice was accepted from the poor, yet the same ceremony was used for the rich; their souls are as precious, and Christ and his gospel are the same to both. Even for the poor one lamb was necessary. No sinner could be saved, had it not been for the Lamb that was slain, and hath redeemed us to God with his blood.