Bahz ibn Hakim reported from his father who from his grandfather that he asked the Prophet (SAW) from whom they should conceal their awrah and from whom not. He said, “Guard your awrah except from your wife and what your right hand possesses (female slaves).” He asked, “O Messenger of Allah (SAW) what when people are with each other?” He said, “If it is possible that no one may observe your private parts, see that none sees them.” He asked, “O Prophet (SAW) of Allah what if one of us is alone?” He said, “But Allah has more right that people should be ashamed before Him.”
[Ahmed 20054]