Mu’aawiya ibn Haida said, when asking about the awrah of a man:
“O Messenger of Allah, what about when one is alone?“
The Prophet said:
“Allah is more deserving of your modesty than are the people.” [Ahmad, Abu Dawood, Tirmidhee and others: Saheeh].
Aishah narrated that the Prophet (saw) said:
“Every woman who removes her clothes other than in her house has torn down all veils of modesty between herself and Allaah.” [Tirmidhee, Abu Dawood and others: Saheeh]
Umm ad-dardaa narrated that the Prophet (saw) said:
“By the One in whose hand is my soul, every woman who removes her clothes anywhere except the house of one of her mothers has torn down all that veils her before Ar-Rahman.” [Ahmad: Saheeh]