While it is easily understood that praying in the vicinity of filth or excrement is inappropriate, the Gemara on today’s daf teaches that a chamber pot is always considered to be disgusting, even if it is clean.
The Sages taught: Opposite a chamber pot used for excrement or urine, it is prohibited to recite Shema, even if there is nothing in it, as it is always considered filthy.
In light of this ruling the Gemara discusses what can be done to avoid the problem of reciting the Shema with a chamber pot in the room.
Rav Yosef said: I raised a dilemma before Rav Huna: It is obvious to me that a bed under which there is a space of less than three handbreadths is considered connected [lavud] to the ground as if the void beneath it does not exist, as halakhah considers a void of less than three handbreadths as sealed. What, then, is the dilemma? What is the halakhah if that space is three, four, five, six, seven, eight or nine handbreadths? He said to him: I do not know. However, with regard to a space greater than ten handbreadths I certainly have no dilemma, as it is clear that this space is considered a separate domain. Abaye said to him: You did well that you did not have a dilemma, as the halakhah is that any space tenhandbreadths high is a separate domain.
The Tosafot R”I explain that there are two basic measurements established here: A space of less than three handbreadths is considered as if it were connected, so any void smaller than this is considered non-existent with regard to practical demarcation of limits and boundaries. Ten handbreadths, however, establishes not only a significant separation, but a separate domain in and of itself. Since their beds were covered along the sides, anything less than three handbreadths is considered connected, while more than ten is considered a separate room.