Seeking Permission to enter (somebody's House) and Manners relating to it

Riyad-us-Saliheen 876
Umm Hani (May Allah be pleased with her) reported: I went to the Prophet (PBUH) who was taking a bath while Fatimah was screening him. He asked, "Who is there?" I replied: "I am Umm Hani."

[Al-Bukhari and Muslim]