Related על ברכות 45:25

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)