English: “Whole stones” — that were not damaged by iron. “You shall not lift iron upon them” — for iron was created to shorten life, and the altar was created to lengthen days.
In Sifrei: The ban on iron on the altar stones is given a moral valence: the instrument of violence has no place on the instrument of atonement.
Type of Learning
Custom (halachah + aggadah of the iron ban).
What Is Learned
The altar of Har Eival was built of whole stones untouched by iron; iron’s association with death excludes it from the altar.