'One's' in the Bible

The religious service which is pure and stainless in the sight of our God and Father is to visit fatherless children and widowed women in their time of trouble, and to keep one's own self unspotted from the world.

let the [latter] one know that the one who has turned a sinner from the error of his way will save that one’s soul from death and cover a multitude of sins [that is, obtain the pardon of the many sins committed by the one who has been restored].