Ambrose of Milan

But the Church has oil wherewith she dresses the wounds of her children, lest the hardness of the wound spread deeply; she has oil which she has received secretly. With this oil Asher washed his feet as it is written: "A blessed son is Asher, and he shall be acceptable to his brothers, and shall dip his feet in oil." With this oil, then, the Church anoints the necks of her children, that they may take up the yoke of Christ; with this oil she anointed the Martyrs, that she might cleanse them from the dust of this world; with this oil …

Letter 41, Section 20 ↗