“I am a shield for you” – Rabbi Levi said two [interpretations], the Rabbis said one. Rabbi Levi said: Because our forefather Abraham was fearful, and saying: ‘Perhaps those people whom I killed, there was among them one righteous man, or one God-fearing man.’5And therefore I have incurred God’s wrath and will be held accountable. This is analogous to a person who was passing by the king’s orchard.
He saw a bundle of thorns and he went down and took it away. The king peered out and saw him. He began hiding from him. He [the king] said to him: ‘Why are you hiding from me?
How many laborers would I have needed to gather it up. Now that you have gathered them up, come and collect your reward.’ So, the Holy One blessed be He said to Abraham: ‘Those people whom you killed were like cut thorns.’ That is what is written: “Peoples will be like burnings of lime, cut thorns ignited with fire” (Isaiah 33:12).
Rabbi Levi said another interpretation: Because our forefather Abraham was fearful, and saying: ‘Perhaps those kings whom I killed, their sons will assemble multitudes and they will come and wage war against me,’6To avenge their fathers’ death. the Holy One blessed be He said to him: “Fear not, Abram, I am a shield for you” – just as a shield, even if all the swords [in the world] were to come up against it, it would withstand them, so you, even if all the idolaters were to gather against you, I will fight against them.
The Rabbis said one: Because our forefather Abraham was fearful, and saying: ‘I went down into the fiery furnace and was saved, I went down to do battle with the kings and was saved, perhaps my reward has already been received in this world, and I have nothing [left] for the future.’ The Holy One blessed be He said: “Fear not, Abram, I am a shield [magen] for you” – everything that I have done for you in this world, I did for you without cost,7In Aramaic, magan means gratis. but your reward is allocated for you in the future – “your reward is very great,” just as it says: “How great is the goodness You have in store for those who fear You” (Psalms 31:20).