Or HaChaim on Exodus 23:9/אור החיים על שמות כ״ג:ט׳

1 ואתם ידעתם את נפש הגר, "and you are familiar with the way a stranger feels." Compare what I have written on 22,20 "you must not disadvantage the stranger." The present verse is proof of the truth of what I have written there.