question #3 Sahih Muslim 1201a, Book 15, Hadith 87 : What alternatives does Islam provide for those who cannot perform certain religious duties due to physical discomfort?

The Messenger of Allah (ﷺ) came to me on the occasion of Hudaibiya and I was kindling fire under my cooking pot and lice were creeping on my face. Thereupon he (the Holy Prophet) said: Do the vermins harm your head? I said: Yes. He said: Get your head shaved and (in lieu of it) observe fasts for three days or feed six needy persons, or offer sacrifice (of an animal). Ayyub said: I do not know with what (type of expiation) did he commence (the statement).