Ramban on Genesis 23:4/רמב"ן על בראשית כ״ג:ד׳

1I AM A STRANGER AND SOJOURNER WITH YOU. It was customary for them to have separate burial grounds for each family and one burial ground for the internment of all strangers. Now Abraham said to the children of Heth: “I am a stranger from another land and have not inherited a burial ground in this land from my ancestors. Now I am a sojourner with you since I have desired to dwell in this land. Therefore give me a burying-place for an everlasting possession just as one of you.” However, since Abraham used the word “t’nu (give), [which has the same root as matanah,” (gift)], they suspected that he desired it from them as a gift. They therefore answered him: “You are not regarded by us as a stranger or sojourner. Rather, you are a king. G-d has made you king over us, and we and our land are subservient to you. Take any burial ground you desire, and bury your dead there. It shall be unto you a possession of a burial-place forever since no one of us shall withhold it from you.”