Thus, in this holy verse, it says: "And if you find no one...

Thus, in this holy verse, it says: "And if you find no one therein, still do not enter them until permission is given to you...." Maybe it implies that sometimes there are some persons at home, but someone who is in charge or someone who is the head of household is not present, in this case we are not allowed to enter the house. Or there is not any person in the house.

Or it is possible that the landlord is in neighbour's home or is near to his house, so when he hears our voice or our knocking at the door, he comes and allows us to enter. In this case we can enter the house. Anyway, what is important is that we can not enter a house without permission. Then the verse continues saying: "... And if it is said to you: Go back, then go back, for it is purer for you;..." It refers to the matter that we must not get upset because of a negative answer.

Maybe the landlord is in a condition that he does get displeased if we see him in that way. Or his home or his room is not ready for receiving any guest. Since when we hear a negative answer, we become curious to know its reason and so we start thinking of looking from some hole or…