In Muharram of 626 the Beni Ghatafan, always formidable on account of their size and their desert hinterland, assembled in force at Dzat-al-Rica. Mahomet determinedly marched against them, and once more at the news of his approach their courage failed them, and they fled to the mountains. Mahomet came unexpectedly upon their habitations, carried off some of their women as slaves, and returned to Medina after fifteen days, having effectively crushed the incipient rising against him. The event is chiefly important as being the occasion which led Mahomet to institute the Service of Danger described in the Kuran, whereby half the army prayed or slept while the other watched. A body of men was therefore kept constantly under arms while the army was in the field, and public prayers were repeated twice.
“And when ye go forth to war in the land, it shall be no crime in you to cut short your prayers.... And when thou, O Apostle, shalt be among them and shalt pray with them, then let a party of them rise up with thee, but let them take their arms; and when they shall have made their prostrations, let them retire to your rear: then let another party that hath not prayed come forward, and let them pray with you; but let them take their precautions and their arms.”
The military organisation is being gradually perfected, so that the Mahometan sword may finally be in the perpetual ascendant. This was the chief significance of a campaign which at best was only an interlude in the daily life of prayer, civil and domestic cares and regulations which took up Mahomet’s life in the breathing space before the great Meccan attack.
Mahomet was absent from Medina but fifteen days, and he returned home resolved to take advantage of the respite from war. Not long after his return he happened to visit the house of Zeid, his adopted son, and chanced not on Zeid, but on his wife at her tiring. Mahomet was filled with her beauty, for her loveliness was past praise, and he coveted her. Zeinab herself was proud of the honour vouchsafed her, and was willing, indeed anxious, to become divorced for so mighty a ruler. Zeid, her husband, with that measureless devotion which the Prophet inspired in his followers, offered to divorce her for him. Mahomet at first refused, declaring it was not meet that such a thing should be, but after a time his desire proved too strong for him, and he consented. So Zeinab was divorced, and passed into the harem of the Prophet. And he justified the proceedings in Sura 33: