Breishis 21:25 "And Avraham rebuked Avimelech." Why did Avraham rebuke Avimelech - Rashi in Sanhedrin (85a) says "hochiach tochei'ach es amisecha" only applies to your fellow Jew, and Avimelech was not a Jew? There is an obligation to rebuke a non-Jew, but that din is different from the din of rebuking a Jew. The purpose of rebuking a Jew is for him to do teshuva. We must rebuke a non-Jew because if we do not rebuke him, there will be lawlessness in the world. We rebuke the non-Jew a non-Jew to improve his behavior so it will not be an uncivilized world.
Breishis 20:7 "And now return the man's wife because he is a prophet." The Mishna (Bava Kama 92a) says even though a damager paid the victim for damages (nezek, tzar, ripui, sheves, boshes) he is not forgiven until he asks for forgiveness, as we see from our pasuk, "And now return the man's wife because he is a prophet." Many ask, why does the Mishna learn it from this pasuk, if the Mishna in Yoma (85b) says that sins between man and G-d are forgiven on Yom Kippur, and sins between man and his fellow man are not forgiven until the damager asks the victim for forgiveness, which Rabi Elazar ben Azaryah darshans from a different passuk, "lifnei Hashem titharu?" The answer is that Teshuva includes two separate things: 1) Teshuva removes the status of sinner from the man. For example, if a thief did teshuva, his status of thief is removed and he is kosher to give testimony. 2) Teshuva brings atonement (kapara) for the sin. Regarding kapara, that's learned from the pasuk "lifnei Hashem titharu" for sins between man and G-d and for sins between man and his fellow man there is no atonement until he asks the victim for forgiveness. Our pasuk, "return the man's wife," teaches us that the "shem rasha" is not removed, and he is disqualified midioraissa from testifying, until he asks the victim for forgiveness.