A man asked RasuulUllaah (SallAllaahu ‘alayHi wa ‘AaliHii Wasallam)! Should I seek permission to enter where my mother lives? He (SallAllaahu alayHi wa AaliHii Wasallam) replied: Yes. This man said: Even if I live in the same house with her? RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Seek her permission. The man said: I serve her (so I have to go frequently). RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Seek her permission, would you like to see her naked? The man said: No. RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Well, then seek her permission

A man asked RasuulUllaah (SallAllaahu ‘alayHi wa ‘AaliHii Wasallam)! Should I seek permission to enter where my mother lives? He (SallAllaahu alayHi wa AaliHii Wasallam) replied: Yes. This man said: Even if I live in the same house with her? RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Seek her permission. The man said: I serve her (so I have to go frequently). RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Seek her permission, would you like to see her naked? The man said: No. RasuulUllaah (SallAllaahu alayHi wa AaliHii Wasallam): Well, then seek her permission

Reference:  http://muntakhabahadith.com