Building al-Masjid al-Nabawi was the first thing God's Messenger (s) did in Medina. Such an achievement indicates the important role of mosque in Islam. This is the most honorable mosque after al-Masjid al-Haram in rank. About saying prayer in this mosque, the Prophet of God (s) says: "For God, a prayer in my mosque equals ten thousands prayers in the other mosques, except al-Masjid al-Haram where a prayer equals one hundred thousand prayers."
Most historians believe the initial area of the mosque had approximately been 1060 square meters, i.e. 35 meters length and 37.5 meters width. But after the Prophet (s) returned from the Battle of Khaybar in 628 CE, the mosque area was increased because of the increase in the number of Muslims and each of its length and width was enlarged nearly 50 meters and its area came up to 2475 square meters and consequently, the mosque turned into a square in shape.