Prayer next to dirt

If someone prayed, and part of the time that he prayed, there was excrement or something really dirty next to him, does he have to repeat the prayer again?

If the excrement was next to him at the time that he was saying something, which is essential for the validity of his prayer, such as one of the blessings (the words “blessed are You”, etc.), or “may it rise and come” (“yaale ve-yavo”), or “give dew and rain”, then he has to repeat his prayer. The rule is that whatever he says while the excrement is next to him, is considered as if he did not say it at all.