G-d said to Abram, "Go for yourself from your land, from your relatives, and from your father’s house to the land that I will show you."
The Torah surprises us with a special mission for our forefather Abraham, without explaining why. By Noah, for example, the Torah explains "These are the offspring of Noah – Noah was a righteous man, perfect in his generations; Noah walked with G-d". However, in regards to Abraham the Torah does not explain why he was chosen.
Nachmanides (Genesis 12:2) describes the difficulty:
Now in this section Scripture does not elaborate on the entire subject at hand. For what would be the reason that the Holy One, Blessed in He, would tell Abraham, "Leave your land and I will bestow upon you goodness, the likes of which have never before existed in the world," without first stating that Abraham served G-d or that he was a wholly righteous person?
Our Sages dealt with this difficulty, and as a result explain that another story happened before choosing Abraham. A few verses before Lech Lecha that Torah says (Genesis 11):
Terah took his son Abram, and Lot the son of Haran, his grandson, and his daughter-in-law Sarai, the wife of Abram his son, and they departed with them from Ur Kasdim to go to the land of Canann; they arrived at Haran and they settled there.
What happened in Ur Kasdim? Our Sages tell us the well-known Midrash about Abraham who saw his father’s idols and broke them, despite endangering his life, and as a result they threw him into the fire and he was saved.
Nachmanides (Genesis 12:2; Genesis 11:28) explains that Abraham was chosen as a result of this story and as a result of the trials that G-d tested him and Abraham withstood them all.
However, the Maharal (Netzach Yisrael 11) explains differently:
It is surprising that Scripture does not mention before this that Abraham was a righteous person…
However, according to what we said there is no difficulty… since this selection was not dependent on any merit, and therefore it cannot be voided.
The Maharal explains that the selection of the Nation of Israel is a Divine selection, and a Divine decision, Who chose Abraham and his descendants, and is not related to Abraham’s previous deeds. This is not an individual selection of Abraham, but a selection of the Nation of Israel; a selection of Abraham and his descendants. G-d decided that Abraham’s descendants are suitable to be His representatives in the world, G-d put in these descendants a special quality which gives them strengths that enable them to keep G-d’s commandments in the world. Therefore, even if Israel sins, they still have within them the special inner quality and they are still the chosen nation. G-d does not say why He chose Abraham, in order to teach us that this is a selection which is not dependant on anything, and even if G-d forbid the Nation of Israel does not act properly they still remain G-d’s nation (but of course, when Israel does not act properly it does not succeed in using its special strengths, and is punished for its deeds. But even in such a situation, it still remains G-d’s nation).
The Sfat Emet brings a new and surprising explanation:
"Go for yourself" is said by G-d to all people always…and Abraham heard and accepted.
The call of "Go for yourself" is always echoing in the world. Since the creation of the world, G-d proclaimed how to do His will in the world. Since the creation of the world, G-d proclaimed a mission of going out to repair the world with G-d’s kingship. Abraham was the one who was ready to implement G-d’s call. Abraham was the first to go after the "Go for yourself" and really worked with all his might to uphold G-d’s will in the world.
The call of "Go for yourself" echoes until today. G-d says His will, G-d gives us missions to achieve and do good in the world, to do kindness, to keep the commandments, to learn Torah, to fill the world with good. We need to listen to that call. Whoever knows how to listen will hear G-d’s voice calling "Go for yourself", and will know to continue working and benefiting the Nation of Israel and the whole world.