Bowing Down

לא תעשו לכם אלילם ופסל ומצבה לא תקימו לכם ואבן משכית לא תתנו בארצכם להשתחות עליה כי אני י_וה אל_יכם:

You should not make idols, neither should you rear you up a graven image, or a pillar, neither should you place any figured stone in your land, to bow down unto it; for I am the L-RD your G-d. (VaYikra 26,1)

MitzvahDescriptionParshaLaws of BH"GRabbi Saadya GoanRE"HRY"BRSl"GYeriimRambamSmagRE"MRambanM"HChinuchSmakZ"HChofetz ChaimNot to bow down on smooth, decorated, mosaic stone, even to HaShem besides in the Beis HaMikdashBehar 26,1Idolatry and Paganism#130104815919435012432741291349181218161

This prohibition is against placing a stone on the ground outside of the Temple so as to prostate oneself upon it in worship. As a rule, a place is permanently marked for all time by a stone being set into the ground. Only in the Temple is one allowed to throw oneself down full length (פשוט ידים ורגלים) praying to G-d, expressing entire surrender to G-d. This prohibition is similar to the prohibition against bringing sacrifices outside the Temple (these sorts of service where only to be done in the Temple). (Horev paragraph #718)

The prohibition is to perform a total prostration of the body with arms and legs extended on a floor of stones (similar to our current custom on Yom Kippur when we prostrate on covered floors). This prohibition also applies even if one has intention to bow to HaShem on stone floors, since it appears similar to the practices of idol worship. (O.C. 131)

Since this verse using the phrase בארצכם this limits the prohibition to not apply in the Bais HaMikdash. Rambam explains that the Torah forbade this worship of HaShem outside of the Bais HaMikdash because it is a form worship used by idolaters.

Two methods exist in which the prohibition of prostration would not apply:

1. One has something separating oneself from the floor (cloth, carpet, etc.).
2. One inclines one’s face to either side (left or right) and does not place one’s face directly to the floor.

Our custom nowadays is not to prostrate but to “fall on our face” (נפילת אפים) during the Tachanun prayers, assuming a sitting position and cover our face with an item of clothing (like a jacket sleeve or a tallis).

A special form of bowing exists call Kiddah קידה. This form of bowing was extremely difficult. The bower would bring his face to the ground from a standing position, using no more than his thumbs for support in front, and then rising.