In addition to the armies in the field, Omar arranged that a reserve of cavalry should be maintained at the head-quarters of the several provinces, in proportion to their resources, ready to be called out upon emergency. The corps at Kûfa numbered 4,000 lances, and there were eight such centres. Reserves for forage were also everywhere set apart; and the cost of these measures formed a first charge upon provincial revenue. [Sidenote: Corân; how ‘collected.’] The various Suras and fragments of the Corân had by this time been compiled into a single volume. The ‘collecting’ of these was begun in the reign of Abu Bekr, at the suggestion of Omar, who was alarmed at the loss of so many of those, who had the Revelation by heart, in the battle of Yemâma. ‘I fear,’ he said to Abu Bekr, ‘that slaughter may again wax hot amongst the Reciters of the Corân in other fields of battle, and that much may be lost of the divine text; now, therefore, give orders speedily for its collection.’ The commission was given to Zeid ibn Thâbit, who, as the Prophet’s amanuensis, had written down much of the revelation from the Prophet’s lips. At first he scrupled to do what Mahomet himself had left undone. At last he accepted the task; and seeking out the Suras and scattered fragments and verses from every quarter, ‘gathered them together from date leaves, shreds of leather and parchment, shoulder blades, tablets of white stone, and the breasts of men.’ By the labours of Zeid, these confused materials were reduced to the comparative order and sequence in which we now find them; but in its obscurity and incoherence, the collection still bears traces in almost every page of the haphazard way in which the pieces, thus rudely dovetailed, were compiled. The original copy was committed to the custody of Haphsa, Omar’s daughter, one of the Prophet’s widows; and during Omar’s Caliphate this exemplar continued to be the standard and authoritative text of the Corân.[355] CHAPTER XXIII. FAMINE AND PLAGUE. A.H. XVIII. A.D. 639. [Sidenote: The _Year of Ashes_. A.H. XVIII. A.D. 639.] The fifth year of Omar’s Caliphate was darkened by the double calamity of pestilence and famine. It is called ‘The Year of Ashes;’ for the dry air of the Hejâz was so charged with the unslaked dust of the parched and sandy soil as to obscure the light by a thick and sultry haze.[356] [Sidenote: Famine in the Hejâz.]