...Then the Khalif himself went thither, and Ka'ab was with him. Said 'Omar to Ka'ab: "O, Abu Ishâk, knowest thou the position of the Rock?" and Ka'ab answered: "Measure from the wall which is on the Wâdî Jahanum so and so many ells; there dig, an ye shall discover it" adding: "At this present day it is a dungheap." So they dug there, and the Rock was laid bare. Then said 'Omar to Ka'ab: "Where sayest thou we should place the Mosque, or, rather, the Kiblah?" Ka'ab replied: "Lay out a place for it behind the Rock, whereby you will make one the two Kiblâhs, that namely, of Moses, and that of Muhammad." But 'Omar answered him: "Thou hast leanings still towards the Jews, O Abu Ishâk. The Mosque shall be in front of the Rock (not behind it.)"