Performing two supererogatory Rak`ahs before Fajr Prayer suffices for Tahiyyat-ul-Masjid

A: If a Muslim enters the Masjid after Adhan (call to prayer) of Fajr (Dawn) Prayer, he should offer two Rak`ahs only which is the supererogatory Salah of Fajr. This Salah is one of the most confirmed optional Salah as related on the authority of `Aishah (may Allah be pleased with her) that she said: The Prophet (peace be upon him) was never more caring in offering any of the supererogatory prayers than the two Rak`ahs of Fajr. Agreed upon by Al-Bukhari and Muslim. Moreover, Muslim narrated that the Prophet (peace be upon him) said: The two Rak'ahs performed before Fajr (Dawn) Prayer are better than this world and what it contains. These two Rak`ahs suffice for Tahiyyat-ul-Masjid as a kind of integration of the acts of worship. That is to say that offering a supererogatory Salah owing to entering a Masjid is integrated in offering a supererogatory Salah of Fajr (Dawn) Prayer which is required owing to the emerging of the time of Fajr. Therefore, if you enter the Masjid after the Adhan of Fajr, you should offer the two supererogatory Rak`ahs of Fajr and do not offer the two supererogatory Rak`ahs of Tahiyyat-ul-Masjid. However, if you offer the two supererogatory Rak`ahs of Fajr at home then you enter the Masjid before Iqamah is performed, it is desirable for you to offer Tahiyyat-ul-Masjid before Iqamah according to the soundest opinion of scholars.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.