"and there is no saving (from sin) from My hand": Fathers do not save sons. Abraham does not save Yishmael, and Israel does not save Esav. This tells me only that fathers do not save sons. Whence do I derive that brothers do not save brothers? From (Psalms 49:8) "A brother cannot redeem another": Isaac cannot redeem Yishmael, and Yaakov cannot redeem Esav. Even if he gives all the money in the world, he cannot ransom him, viz.: "A brother cannot redeem another … (9) Too costly is their souls' redemption and forever unattainable." How precious is this soul! When one sins, there is no payment for it!
Abraham and the Patriarchs of Esav
Sifrei Devarim 329:4