Thousands of supporters of various Egyptian Salafi groups gathered in Cairo's Tahrir Square calling for the immediate implementation of Islamic law.
Before midday prayers, speakers called on the government of President Mohamed Morsy to move quickly to implement Sharia. Morsy won the office as the candidate for the Muslim Brotherhood-affiliated Freedom and Justice Party.
About 10,000 demonstrators advocating for Sharia filled the square, chanting in unison, "The people want God's law applied."
Egypt is formulating a new, post-revolutionary constitution, and Sharia's place in the process is highly contentious -- dividing Islamists and secularists, and even Islamists themselves. The Muslim Brotherhood is in favor of gradual implementation of Sharia, while the Salafis want it imposed immediately.
Many Egyptians complain that the country should focus on cutting poverty and unemployment, reviving the flagging economy and fighting corruption.
Egypt's Coptic Christian minority, which makes up between 8% and 10% of the population, is adamantly opposed to the demands by the Salafis and their allies for Sharia's implementation.
The recently elected Coptic pope, Tawadros II, has expressed his opposition to Egypt's adaptation of a religious constitution.
Demonstration organizers set up a large stage and sound system overnight. Residents in the neighborhoods around Tahrir slept fitfully as the sound system blasted religious songs and prayers starting at midnight.
The two main organizers are the Gama'a Islamiya, which fought against the security forces of ousted President Hosni Mubarak, and the Salafi Front, which was founded after Mubarak's departure. Earlier this week, the Muslim Brotherhood and the Salafi Nour Party declared they would not participate in the event.
Such demonstrations, by groups across the political spectrum, have become an almost weekly occurrence since the ouster of the Mubarak regime in February 2011.