Abu Bekr became anxious at the delay, and at the urgent appeals that came to him for reinforcements. It was not so much the poverty of numbers, as the lack of fire and military genius that disquieted him. Abu Obeida was mild and kindly even to timidity; Amru an able counsellor, but lacking military dash. The mettle of none of the generals had yet been fully tested; and their independence one of another, in the absence of a general-in-chief, while it gave opportunity to each, had a paralysing effect on all. When, therefore, the cry reached Medîna for help, the Caliph exclaimed: ‘Khâlid, son of Welîd, is the man for this! By him, with the help of the Lord, shall the machinations of Satan and the Romans be overthrown.’ The stealthy pilgrimage of Khâlid had come to his knowledge, and he now marked his displeasure by indirectly hinting at it in the order for his deputation to Syria, which ran as follows: ‘Depart and join thyself unto the armies of the Faithful on the Yermûk, for they are downcast and forlorn. But beware that thou return not again to do what thou hast done. The Lord helping, thy removal shall not dishearten thy followers in Irâc. Go forward then, Father of Suleimân, high resolve and success attend thee! Fill up the measure of the Lord’s benefits upon mankind, and He shall fulfil the same unto thee. Have a care lest the world and the flesh ensnare thee, so that thou stumble and thy works perish. The Lord doth recompense!’[160] [Sidenote: Khâlid, with reinforcements from Irâc, sets out for Syria.] This order at the first disconcerted Khâlid. He set it down to Omar, who, envying him the conquest of Irâc, would thus, on the eve of accomplishment, snatch it from his hand. There was too much reason for the fear; but had Abu Bekr lived, it would have been otherwise, for his order continued thus:--‘Take with thee half the army, and leave Mothanna half. [Sidenote: Safar, A.H. XIII. April, A.D. 634.]When the Lord shall have given thee victory in Syria, then thou shalt return with the troops to thy command in Irâc.’ Reconciled by this assurance, and loyal to his chief, Khâlid set to work at once, and began by selecting the ‘Companions’ and flower of the force to accompany him. Mothanna insisted that the division should be equal both in kind and number, and protested that he would not be responsible for the safety of Irâc unless it was effected fairly. He was conciliated by getting back a goodly portion of the veterans. The strength of either moiety is put at 9,000.[161] The spring was far advanced when Khâlid marched. Mothanna accompanied him to the border of the desert, and, taking a last farewell of the great general whom he had served so loyally, retraced his steps to Hîra. [Sidenote: Khâlid marches across the Syrian desert;]