Umar, the second Caliph, refused to pray inside the Church of the Holy Sepulchre in Jerusalem when invited by the Christian Patriarch Sophronius because he feared a small chance future Muslims use his prayer as an excuse to take over the church and convert it into a mosque. `Umar ibn Al-Khattab entered Bayt Al-Maqdis, and came to the Church of the Resurrection and sat in its courtyard. When the time for prayer came, he said to the patriarch: I want to pray. He said to him: Pray where you are. But he refused, and he prayed on the doorstep of the church, on his own. Then when he had finished praying, he said to the patriarch: If I had prayed inside the church, the Muslims after me would have taken it (as a mosque) and they would have said: `Umar prayed here. And he wrote for them that they were not to gather to pray on the steps and that Adhan was to be given from that location. (End quote from Tarikh Ibn Khaldun, 2/225)