From the Rav’s Desk: Does the altar become invalid if metal merely touches it?

  1. Question: [Wednesday, 20th Menachem Av 5782]

I heard something very novel and interesting in a speech by a rabbi the other day that if metal even touches the altar, then the altar becomes invalid. Thus, if one of the priests accidentally touches the altar with a metal knife or with his metal watch, then the stone which it touches is invalid and must be removed and replaced. I always thought that the invalidation applies only if the stone becomes blemished due to the metal and not simply due to it touching the altar. Can you please clarify this for me?


It is indeed correct that the Rambam, based on the wording in the Mishneh in Miseches Midos, makes such a statement, that if iron even touches one of the stones of the altar, then that stone becomes invalid for the altar. This means that it can no longer be used for the building of the altar, and if it was a already used for the building of the altar, then it must be removed and replaced. Nonetheless, there are Mefarshim, and Poskim, who explain this to not be taken literally, as in truth there is no source in scripture for stating that the mere touch of iron to the stone invalidates its use for the altar. Rather, the intent of the Rambam, and the final ruling, is that if the stone was split using iron, then it is invalid even if no part of the stone became chipped in the process, as the Torah explicitly negates the use of an iron hewed stone for the sake of the altar or its ramp even if the stone is not blemished. If, however, iron simply brushes or touches the stone without chipping or blemishing it, and without cutting or splitting it, then the stone remains valid to be used for the altar and certainly does not become invalid when already built. From other Mefarshim, however, as well as from the simple wording of the Rambam, it is implied that even a mere touch of iron invalidates. Thus, the above statement which you heard is in truth under debate amongst the Poskim as to its accuracy. In addition, it should be noted that the above issue is specifically with iron, however, other metals may be used for the stones of the altar and do not invalidate it. Hence, if a gold or silver vessel touches the stone of the altar, it does not become invalid according to any opinion, as writes the Ramban on Yisro 20:22. Accordingly, if the high priest touches the altar with his gold garments it does not become invalid. Likewise, if a person wearing a gold watch accidentally touches the altar it does not become invalid.

Explanation: Scripture [Yisro Chapter 20:22] states that one may not build the altar with hewed stones as you have waived your sword over it and desecrated it. From here it is derived in the Mishneh Miseches Midos that one may not hew the stones of the altar with iron. The Mishneh then concludes that the reason for this is because iron invalidates the altar even with touch. It is based on this Mishneh that the Rambam writes two separate laws relating to the stones of the altar, one in relation to a blemished stone which is invalid for the altar irrelevant of how it became blemished, and another in relation to a stone which touched iron, which is invalid for the altar even if it did not become blemished. However, some Mefarshim explain this to not be literal being that there is no scriptural support for invalidating mere touch of iron, and even the Rambam himself who brings a scriptural proof for his ruling, brings the verse that discusses cutting a stone using iron. Hence, they are forced to explain that the Rambam’s intent is not mere touch of iron, but rather the use of iron to cut the stone, and only then is it invalid.


Sources: See Torah Shleima Ki Sisa footnote 550; Taryag Mitzvos Hashaleim Vol.3 p. 56; Harambam Hamevuar Hilchos Beis Habechira p. 18; Regarding the statements of the Rambam see: Rambam Hilchos Beis Habechira 1:14 “Any stone which is damaged to the point that a fingernail would get caught in it when passing over it, is invalid for use for the Altar and for its ramp.”; 1:15 “Any stone which has touched iron is invalid for use for the building of the Altar or the ramp, and one who does so is liable for lashes. This applies even if the stone was not damaged because of the iron.”; 1:16 “If a stone of the altar or its ramp was damaged or touched by iron then although that stone becomes invalid, all the other stones remain valid.”; Rambam Sefer Hamitzvos Mitzvah Lo Sasei 79 “We were warned not to build the altar from stones that touched metal”; Poskim and Mefarshim who interpret the above statements to not be literal: Lechem Yehuda on Rambam ibid Chapter 1 Halacha 16 according to Raavad; Aruch Hashulchan Ha’asid Beis Hamikdash 4:9; Yireim 396 [Hashaleim-310] and Toafas Riem there 1; Implication of Mechilta; Possibility brought in Pirush Hazharos Lerashbag; Kiryat Sefer Azharas 198; Mateh Aaron; Rambam La’am on Beis Habechira 1:15-16; Poskim and Mefarshim who interpret the above statements to be literal: Implication of Miseches Midos 3:4; Implication of Rambam ibid and Setimas Hamefarshim there [i.e. Kesef Mishneh, Lechem Mishneh]; Rosh Midos 3:4; Mechilta Derashbi Shemos 20:22; Sefer Hachinuch


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