I will make you a great nation and I will bless you and I will make your name great and you will be a blessing. (Gen. 12:2)
Nachmanides tell us that we should aspire to be blessed in Abraham's name. As Nachmanides comments on the phrase from Genesis 12:2, "and you will be a blessing": "You will be the blessing by whom people will be blessed, saying, "God make you like Abraham."
The theme of blessing returns in a later passage, Genesis 26:1-5. This passage helps explain (a) how Abraham would be a blessing, and at the same time (b) what it would mean for God to "make you like Abraham." After Abraham's death, God appears to Isaac, significantly in a time of famine: "there was a famine in the land, aside from the earlier famine that was in the days of Abraham." (v. 1) God orders him to remain in the land promised by oath to his father Abraham: "Sojourn in this land, and I will be with you and I will bless you.... I will increase your offspring as the stars of heaven, and I will give to your offspring all these lands, and in your offspring all the nations of the earth will be blessed, inasmuch as Abraham listened to my voice and kept my requirements, my commandments, my laws, and my teachings." (vv. 3-5)
How would Abraham, through his offspring, come to be a blessing to all the nations of the earth? Inasmuch as, eiqev asher, along with what follows, is one key to understanding Abraham's greatness. Abraham could be a blessing because "Abraham listened to my voice and kept my requirements, my commandments, my laws, and my teachings." And these teachings he passed on to the next generation, "to keep the way of the Lord, to do what is right and just." (Gen. 18:19) That Isaac carries on the blessing of his father Abraham is the central point of Genesis 26:1-5.
In short, Abraham was faithful, as we read elsewhere: "You found his heart faithful before you." (Nehemiah 9:8; cf. Gen. 15:6)
To do what Abraham did took incredible courage and commitment, for at the beginning of his journey, when he left behind his land, his birthplace, and his father's house, he also left behind his family's religion. As Joshua 24:2 tells us, Abraham's father "worshiped other gods." Abraham did not follow tradition, or comfortably conform to his father's religion, but chose to listen to a different voice. That same voice continues to call: "Listen to me, you who pursue righteousness, you who seek the Lord. Look to the rock from which you were hewn, to the quarry from which you were dug. Look to Abraham your father and to Sarah who brought you forth. For he was only one when I called him, but I blessed him and made him many." (Isaiah 51:1-2)
While some look to Abraham (and Sarah) as native-born descendants, others look to Abraham (and Sarah) as converts, who like him, only one, leave behind their family's religion when God calls them out and blesses them with "the law of life, and the love of kindness, righteousness, blessing, mercy, life and peace." [From the Sim Shalom benediction]