This is the second book of the Mishneh Torah of the Rambam, Rabbi Moshe ben Maimon. Laws of Reading the Shema.
This chapter explains what happens when the time for reciting the Shema arrives and no water is found, the places where it is forbidden to recite it, whether it is a bathhouse or a new bath, whether it is permissible to say holy things in secular language or vice versa, whether the opportunity arises to separate someone from something forbidden in the bath, what kind of excrement is forbidden to recite the Shema in front of, how dry it must be and the law of moving away from it in order to recite it, whether there was something that interrupted it or placed a container over it, how much water is necessary for urinating at once, a drop of excrement on one's skin or in its place or if one's hands were dirty, excrement that passes, the pig's mouth or if one arrived at a dirty place, who reads in the house or in a garbage dump and has doubts about whether there is excrement or not, what kind of nakedness is forbidden to recite it in, whether one slept naked with one sheet or two sleeping under the same sheet, who sleeps with his wife and small children and until when they are considered small.