An-Nur · 24:58

58. O those who have faith in Allah and act upon the laws set for them! Your free immature children, male servants and female servants should seek permission from you thrice, at three times: before the morning prayer at the time of changing from nightwear into daily clothes, in the afternoon when changing clothes for the siesta and after the night prayer because it is the time when you remove your daywear and change into your nightwear. These are three times of privacy for you; they should not enter your rooms except after taking permission from you. Apart from these times, there is no harm in them entering your rooms nor you entering theirs, because you frequently have to move around one another and so it would be an inconvenience to prevent them from entering except with permission. Just as Allah has made the rulings of seeking permission clear to you, He also makes clear the verses that show the rulings He has laid down for you. Allah is ever-aware of the requirements of His servants; wise in whatever laws He passes for them.