"Believers, you are required to pray together each Friday. When you hear the call to prayer, stop your worship, and hurry to the place of meeting. This will do you much good--if you only knew. When the prayers are finished, disperse, and seek God’s grace. Keep God always in your mind, so that you may enjoy success in your work. "
-Qur'an, Al-Jumu'ah, Surah 62:9-10

From "366 Readings From Islam," translated by Robert Van der Weyer. Copyright 2000.