Is every prayer performed in Quba Mosque, such as Fajr prayer and Tahiyyat al-Masjid (greeting to the mosque), rewarded with the equivalent of an 'Umrah, or is that limited to supererogatory (nafl) prayers only? And is it legislated to continue performing the two rak'ahs of prayer upon entering the mosque until the Imam prays?

The reward for prayer in Quba Mosque is immense, and the Hadith stating that praying two rak'ahs therein is equivalent to the reward of an 'Umrah is authentic. This includes تحية المسجد (greeting the mosque prayer), voluntary prayers, and obligatory prayers. The reward of 'Umrah was initially prescribed for four rak'ahs, then it was eased to two rak'ahs. Engaging in supererogatory prayers until the time for obligatory prayer arrives is good, and prayer is the best subject [of occupation]. For one who finds engaging in other forms of dhikr (remembrance of Allah), supplication, and Quran recitation more beneficial for their heart than prayer, there is no harm in that, because the rectification of the heart is the aim of righteous deeds.