Sefer HaChinuch, Mitzvah 600

We Jews have been commanded to rescue the pursued from the hands of any who pursue them with intent to kill, if necessary at the cost of the pursuer's life...Among the roots of this commandment is that God, Who is Blessed, created the world and willed that it be settled, and the settlement of the world is upheld by the championing of the weak against those stronger. Furthermore, the pursued will always have eyes and heart turned toward God to champion him against his pursuer, as Scripture says, "The Lord will seek out the pursued"- meaning that the pursued seeks the Lord and prays. Therefore, the Blessed One has commanded us to assist the pursued. [Translation by EDAH and the Center for Modern Orthodox Torah Leadership. Edited for gender neutrality]