It's also called the valley mosque. It named Friday mosque because when the prophet Mohammed, peace be upon him, went out of Qiba heading to Medina Friday prayer, Al Gomaa prayer, time comes so he prayed it there at the middle of a valley. The mosque was built where the prophet Muhammad peace be upon him prayed. The Friday mosque is 500 meter far away from Qiba mosque and 2500 meter far from the prophet holy mosque. The mosque still exist there and its well known for the people of Medina and many visit it.