Related for Berakhot 45:1
מר סבר אם שהה כדי לגמור את כולה חוזר לראש ומר סבר למקום שפסק
One is of opinion that if the man has waited sufficient time to finish the remainder of the Tefillah, he should recommence from the beginning. The other is of opinion that [in any event] he should go back only to the point where he stopped.
Tosefta Berakhot
A person should not go into dirty alleyways and read the Shema [there]. And not only that, but even if he already walked into [a dirty alleyway] while he was reading [the Shema], he should stop [reading it] until he completely exits from that area, and [only then] he [may continue] reading [the Shema]. A person should not stand and pray [Shmoneh Esreh] while he needs to relieve himself, as it is said, “Prepare to greet your God, Yisrael.” (Amos 4:12)
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