281. Davening in a Clean Place
Tefillah u’Birkas Kohanim 4:8
The cleanliness of the place where one is to daven (in 4:1) is as follows: One should not daven in a filthy place, a bathhouse, a restroom or a garbage dump. If a place cannot be presumed to be clean, one should not daven there until he makes sure that it is. Generally speaking, one may not daven in any place where he could not recite Shema. Just as one must separate himself from excrement, urine, foul odors, corpses and nudity in order to recite Shema, so must one separate himself from these things in order to daven Shemoneh Esrei.
Tefillah u’Birkas Kohanim 4:9
If a person finds excrement in the place where he is davening, since he violated by not checking the place before he started, he must daven again in a clean place. If one finds excrement while he is in the middle of davening, if he can walk forward so that the offensive matter will end up four cubits behind him, he should do this. If not, he should move to the side. If he can’t do this either, he should stop davening. Great Sages wouldn’t daven in a building where beer or brine was foaming because of the offensive smell, even though it was still a clean place.