Halakhah su Salmi 91:5

It is written, "His angels will be commanded to you, to watch over you on all of your travels". On Shabbos (Meseches (Tractate) Shabbos) 119b we say,"two angles escort a person". In Chagigah 16a, it comes to say, " the two angels that escort this person testify on his behalf". Therefore, the Sages commanded (Brachos 60b) that when one needs to enter the bathhouse, he should say before he enters "be honored, respected and holy ones, the rulers of above! Watch over me! Watch over me! Help me! Help me! Wait for me until I enter and come out, since this is the way of man!". Its explanation: This person is mentioning that the angels are too holy to enter into the bathhouse and therefore, they should wait for him to exit from there. He is asking them to protect him from demons. This is the true meaning of that which is written, "His angels will be commanded to you, to watch over you on all of your travels". Meaning, wherever one is forced to go, even into a place where the angles cannot enter. The mentioned safeguarding is from demons as was written in prior times, "You shall not fear the fright of night...destruction that ravages at noon" (Tehillim 91). This that one says, "Help me!" is in regard to cleanliness since at the exit of the uncleanliness (excrement) is something that dependent upon all beings; therefore, one says,"this is the way of man!", meaning, "what shall be done if someone is forced to do this?".