Ask the Rov: When bowing to the ground in shul, when and where do I put something down as a separation?
By Rabbi Chaim Hillel Raskin – Rov of Anash in Petach Tikvah
The Torah states, “You must not lay an even maskis — a pavement of stones — on which to prostrate yourselves.” This ritual may only be performed for Hashem in the Beis Hamikdash, not anywhere else.1
The prohibition min hatorah applies specifically when it is done: (1) on a floor of stone, (2) one is fully prostrated with spread out arms and legs (hishtachava’a), (3) one’s head is facing straight towards the floor and not tilted to the side.
As a safeguard, Chazal prohibited even cases that meet two of three conditions. Thus, bowing down without lying flat on the ground (kidah) is prohibited on a stone floor miderabonon.2 On a non-stone floor, one may bow, or one may even prostrate completely if they tilt their face so that it doesn’t touch the floor. Kneeling without bowing is permitted even on a stone floor.3
When bowing on Rosh Hashana and Yom Kippur, our custom is to touch our foreheads to the floor, but we don’t prostrate ourselves totally, meeting two out of the three criterion.4 To avoid the prohibition, we put down a cloth when bowing on stone. The separation must be between one’s face and the ground, not at the knees.5 One who doesn’t have any cloth (or tallis) to separate should tilt his head away from the ground.6
In discussing the bowing, the Rama requires a separation, presumably referring to a shul with a stone floor.7 While some poskim require, as an extra precaution, to place a cloth even when bowing on floors of other materials (wood or even carpet),8 Minhag Chabad does not require any separation for a non-stone floor.9 Marble, granite, and cement are like stone, but brick isn’t.10 Tiles of porcelain and ceramic are the subject of dispute.11
What about bending down to get something or while doing exercises? Contemporary poskim write that one may bend down on a kitchen or bathroom floor to retrieve something or to bathe a child since one does intend to bow at all. Similarly, exercise (e.g., push-ups) may be done even on a stone floor since one does not intend to bow.12
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From The Weekly Farbrengen by Merkaz Anash