Rashi on Genesis 12:1/רש"י על בראשית י״ב:א׳

1לך לך GET THEE OUT (literally, go for thyself) — for your own benefit, for your own good: there I will make of you a great nation whilst here you will not merit the privilege of having children (Rosh Hashanah 16b). Furthermore, I shall make known your character throughout the world (Midrash Tanchuma, Lech Lecha 3)