Muhammad's care and preoccupation, therefore, were directed toward the north, not toward the south of Arabia. This was especially so following his return from the "Farewell Pilgrimage." In fact, ever since the campaign of Mu'tah, when the Muslims returned without conquest after the clever and strategic withdrawal of Khalid ibn al Walid, Muhammad had been giving to Byzantium a good portion of his thought and careful planning. He was convinced that Muslim power at the northern frontier with al Sham should be firmly established if those who had been evacuated from the Peninsula and who had emigrated to Palestine were not to return and attack again. It was in consequence of this care that Muhammad mobilized a very massive army when he heard that the Byzantines were about to advance on the northern frontier, and he himself led that army all the way to Tabuk. The Byzantines had withdrawn toward the interior upon hearing of the march of that army. This notwithstanding, Muhammad continued to plan for the day when the lords of Christendom who dominated the world through Byzantium might be stirred to attack in resentment against those who had brought Christianity to an end in Najran and other places in Arabia. Consequently, the Muslims did not stay long in Madinah following their return from the farewell Pilgrimage in Makkah. The Prophet had immediately ordered the mobilization of a large army and commanded it to march on al Sham. That is why he sent along with that army a number of the elders of Islam, the earliest Muhajirun, among whom were Abu Bakr and `Umar. That is why he gave the command of the army to Usamah ibn Zayd ibn Harithah.
Usamah ibn Zayd, the commander of the army, was then a young man hardly twenty years of age. His appointment and precedence over the elders of Islam, the early Muhajirun, and greater companions of the Prophet, would have caused quite a stir among the people had it not been for everybody's genuine faith in the Prophet's judgment and calculation. By appointing him, the Prophet sought to place him in the same command in which his father fell in the campaign of Mu'tah. The Prophet had wanted to give Usamah cause for pride in victory tantamount to a reward for the martyrdom of his father. Moreover, such an appointment was sure to stir within the soul of the youth the greatest resolution, determination, and bravery. It was also meant as an example for the youths of Islam to carry the burden of great responsibility. Muhammad commanded Usamah and his army to enter the approaches of al Balqa' and al Darum in Palestine, in the vicinity of Mu'tah where his father had fallen. He also commanded him to fight the enemy in the early hours of dawn, to fight them fearlessly, and to shower them with fire. He also commanded him to surprise the enemy, never to let the news of his advance reach them beforehand. Once victory was achieved, Usamah was to return home quickly and not to extend his stay in those lands.
Usamah and his army set up their headquarters at al Jurf, in close proximity to Madinah, and there began their preparation for the long trip to Palestine. While they were getting ready, the Prophet of God fell ill and the seriousness of his-ailment prevented their going forth. One may ask with surprise how the sickness of the Prophet of God could prevent an army from undertaking a campaign which he himself had ordered. One must remember, however, that for that army to go to al Sham, it had to cross wide deserts and empty places, a matter that was not at all easy and would take many long days. It was not easy for the Muslims, considering their great love for the Prophet, to leave Madinah while he suffered from grave illness. Those same men knew that the Prophet never suffered from any serious ailment. Nothing had adversely affected his health throughout this period except a brief lack of appetite in 6 A.H. falsely attributed to Jewish magic, and a little discomfort following his eating a bite of poisoned lamb in 7 A.H. Furthermore, the rhythm of his life and the logic of his teachings always protected him against disease. He always ate little and satisfied himself with the barest and simplest necessities. His clothes and his house were always perfectly clean, for Muhammad not only saw to it that the duties of ablutions were perfectly carried out at all times, but he even used to say: "Were it not for my fear of imposing hardship on my people, I would have made it a duty for them to brush their teeth five times a day." On the other hand, the ritual of prayer and daily exercise which Muhammad observed as well as his sense for economy in the pursuit of pleasure, his refrain from indulgences of all kinds, and his general unconcern for things of this world which always kept him at a distance from them, but in communion with cosmic life and the secrets of existence all these aspects of his character protected him against disease and gave him good health. His strong natural, construction and innate inclination to moral goodness consolidated his immunity against disease.
Now that he had fallen seriously ill, however, it was natural for his friends and companions to become concerned and anxious, fearing that the untold energies he spent during the last twenty years of life may have been begun to take effect upon him. Ever since he had proclaimed his prophethood in Makkah and begun to call men to worship God alone, to abandon the idols of the ancestors, Muhammad had met such great opposition and hardship that his companions had to flee to Abyssinia and he himself to the seclusion of the mountains in the outskirts of Makkah. His flight from Makkah to Madinah, following the covenant of `Aqabah, took place under the most trying and dangerous of conditions. Muhammad did not know what awaited him in Madinah before he arrived there under cover of night. When he did arrive there, he immediately became the object of Jewish plotting and intrigue. After God gave him victory following all these trials and permitted men from all corners to join the new faith, Muhammad's duties multiplied to a tremendous extent. The keeping of the peace, the leadership of the community, the establishment of its institutions, the continuous wars he had to fight, and the attacks he had to repel would have broken the back of the strongest man.
What situation could have been more tragically trying than that in which Muhammad found himself at the Battle of Uhud when the Muslims ran away from their enemy and Muhammad ascended the hill alone pursued by Quraysh's soldiers; when, under a shower of enemy arrows and stones, he fell wounded, with his teeth broken? What position could be more frightening than that in which the Prophet found himself at the Battle of Hunayn when the Muslims fell back at dawn before their attacking enemies when so determined was their retreat that Abu Sufyan could say that "Only the sea could make them turn back again"; when in the midst of this retreating stream of people Muhammad held his ground and called unto the Muslims: "Where to? Where to? Come back! Come back to me!" until they returned and were victorious. Moreover, there was the burden of mission, the tremendous burden of revelation, the self exhausting spiritual effort to keep in communion with the reality of the universe, with the supernal plenum-an effort the Prophet was reported to have described as more horrendous than the destiny of doom which befell Hud and other ancient civilizations. Muhammad's companions were witnesses to all this. They had seen him bear his burdens uprightly and with determination, never faltering. Now that he had fallen ill after such a splendid career, it was natural for them to want to postpone their march to al Sham for a while, until they could reassure themselves of God's disposition.