Is the greeting of the mosque prescribed in the mosque library?

The questioner : No, another question.

The Shaykh : Please, what is it?

The questioner : I have another question. Regarding the greeting of the mosque, there is a room inside the mosque, and some of the young men pray the greeting of the mosque in that room, then they go to the mosque and sit down. Is this valid?

The Shaykh : Is the room entered through its own door, or is its door to the mosque such that one cannot enter the room except from the mosque? How is it?

The questioner : The room is entered through the mosque door. This room contains a library with books, and they enter it through the mosque door. They pray two rak'ahs in that library, look at some of the books, and then go to the mosque without praying the greeting of the mosque.

The Shaykh : So, what you call the room is the mosque library.

The questioner : The mosque library, yes.

The Shaykh : So, the prayer there—this library is part of the mosque. Whether one prays in the mosque or in the library, the greeting is obligatory in the library or in the mosque.

The questioner: May Allah reward you with good, O Shaykh.

The Shaykh : And beware of that.

The questioner : O Shaykh.

The Shaykh: Yes.

The questioner : Another question.

The Shaykh : Bring it.

The Shaykh: Yes.