Larger mosques sometimes offer special, optional prayers. They are done after the last required prayer of the day. During each night of prayers, one member of the community who has memorized the entire Qur’an will recite a part of the book. It can last for up to two hours. Sometimes, several such people (not necessarily of the local community) take turns to do this. During the last ten days of Ramadan, larger mosques will host all-night programs to observe "Laylat al-Qadr". It is the night Muslims believe that the Islamic prophet Muhammad first received Qur'anic revelations. On that night, between sunset and sunrise, mosques employ speakers to teach the worshipers about Islam. Mosques or the community usually provide meals at times through the night.