ויאמר ה׳ אל אברם לך לך א״י או״ט די״ט בלע״ז, פירוש בעוד שהיה תרח באור כשדים. ד״א מארצך מחרן שאתה דר שם כדכתיב לעיל ויבאו עד חרן וישבו שם. ויאמר ה' אל אברם לך לך, The Lord said to Avram: “go for yourself, etc;” While Terach and Avram were still in Ur Casdim, G-d told Avram to leave his homeland. He did not specify his ultimate destination. A different interpretation of the words: מארצך, “from your homeland.” “Leave the land in which you are currently residing.”
וממולדתך שלא תאמר אשוב אל ארץ מולדתי אשוב אל בית אבי בשביל ירושתי שהרי אברכך יותר מכדי ירושתך. כאן פרש״י וכאן אי אתה זוכה לבנים הוא שאמרו רבותינו שלשה דברים מבטלים את הגזרה שינוי מקום וקריאת שם וכו' וממולדך, “G-d added this to prevent Avram from returning to his birthplace, Ur Casdim. ומבית אביך, “and from the house of your father.” G-d did not want Avram to ever return to his father’s house in order to receive his share of the inheritance. He promised to reward him far beyond anything he could expect as his share of his father’s estate. Rashi here adds a peculiar comment, writing that here the meaning of בית אביך is that where Avram had resided thus far he would not be able to become a father of children. Apparently, he bases himself on our sages in the Jerusalem Talmud, Taanit: 2,1: that there are three things which are apt to cancel a decree against someone siring children: changing the place of one’s residence, changing one’s name, and observing a fast, praying for children. (Compare also Bereshit Rabbah 44,11)
אל הארץ וגו׳ לפי שהיה מזרעו של שם שנפלה הארץ לחלקו כמו שפרש״י. הוליכו הקב״ה להתהלך בה. אל הארץ, “to the land;” the definitive article ה, is to remind Avraham that seeing he was descended from Shem, he had a legal claim to this land. This conforms to how Rashi (Verse 6) explains why he was instructed to walk throughout this land (Genesis 13,17) in order to claim it through having set foot in it. G-d Himself guided him.