Responsa к Мишлей 3:39

Response: Sacrificing a limb to save a fellow Jew] is a pious trait, but the logical argument could ‎be ‎disputed… Further, perhaps by cutting off his limb, even though his life does not depend upon ‎this ‎limb, he might lose much blood and die. “Who says that you friend’s blood is redder? Perhaps ‎your ‎blood is redder? (See Sanhedrin 74a)” I witnessed one who died resulting from small holes ‎pierced in ‎his ear to remove blood’ he lost so much [blood] that he died, even though man has no ‎limb smaller ‎than the ear! Certainly [he could die] if they would cut it off.‎ Further, it is written [of Torah] “its ways are pleasant ways” [Proverbs 3:17] and the Torah’s laws ‎must ‎be consistent with intellect and logic. How could we believe that one should let someone ‎blind his ‎eye or cut off his arm or leg in order that they not kill his friend?‎ Therefore, I see no reason for this ruling; rather, it is a pious act and praised is the lot of one ‎who ‎could withstand this [sacrifice]. However, if [allowing his limb to be chopped offer would ‎present] a ‎possible risk to his life then such a person would be considered a pious fool, for the ‎doubt [regarding ‎his life] is greater than the certainty of [saving] his friend’s [life].‎