Praise be to Allaah.
Tahiyyat al-masjid (“greeting
the mosque”) is Sunnah according to most of the scholars; some of the
scholars stated that there was consensus on this point.
Abu Qataadah (may Allah be pleased with him) said: The
Prophet (blessings and peace of Allah be upon him) said: “When one of you
enters the mosque, let him not sit down until he has prayed two rak‘ahs.”
Narrated by al-Bukhaari, 1167; Muslim, 714
An-Nawawi (may Allah have mercy on him) said: The scholars
are unanimously agreed that it is mustahabb to greet the mosque, and it is
makrooh to sit down without greeting it with no excuse, because of the
hadeeth of Abu Qataadah which clearly states that that is not allowed.
End quote from al-Majmoo‘, 3/544
Al-Haafiz ibn Hajar (may Allah have mercy on him) said: The
scholars are unanimously agreed that the command in this case is a
recommendation (as opposed to an obligation). Ibn Battaal narrated from the
literalists that it is obligatory, but Ibn Hazm stated that it is not
obligatory.
End quote from Fath al-Baari, 1/538, 539. See also
al-Muhalla, 2/7
It says in Fataawa al-Lajnah ad-Daa’imah (7/137): The
Sunnah for the one who enters the mosque at any time is to pray tahiyyat
al-masjid, because of the general meaning of the words of the Prophet
(blessings and peace of Allah be upon him): “When one of you enters the
mosque, let him not sit down until he has prayed two ra ‘ahs. Saheeh –
agreed upon.
End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The
view that tahiyyat al-masjid is obligatory is a strong view, but the
more likely to be correct is the view that it is a confirmed Sunnah (Sunnah
mu’akkadah). And Allah knows best.
End quote from Majmoo‘ al-Fataawa, 14/354
And Allah knows best.