"… And you see the people enter Allah's Religion in crowds, then celebrate the Praises of your Lord, and pray for forgiveness from Him: for He is Oft-Returning (in Grace and Mercy)."
In the ninth year of the Hijra only one major operation was carried out by the Muslims-the expedition to Tabuk, led by the Holy Prophet in person. It turned out to be a peaceful operation; but no matter how peacefully other people went about their tasks, Khalid always managed to find adventure and violence.
During the long, hot summer of 630, reports arrived at Madinah that the Romans had concentrated large forces in Syria, and had pushed their forward elements into Jordan. Heraclius, the Byzantine Emperor, was himself in Emessa.
In the middle of October 630, the Prophet ordered the Muslims to prepare for battle with the Romans. The purpose of the expedition was not just to fight the Romans, for that could have been done later when the weather had improved. The Prophet also wanted to put the faith of the Muslims to test by making them march out in the fierce heat of summer. Under these conditions only true Believers would respond.
And the true Believers did. The vast majority of the Muslims answered the call cheerfully and began preparations for the expedition; but some did take unkindly to the call to arms. The October of this year was an unusually hot month, and the cool shade of the date orchards proved too tempting for these Muslims. Men wanted nothing more than to rest in the shade until the worst of the heat was over. The Hypocrites, as usual, went about dissuading the Muslims from joining the expedition and gave trouble enough; but on this occasion even a few proven Muslims faltered.
In late October 630 (mid-Rajab, 9 Hijri) the Muslims set out for Tabuk. This was the largest army that had ever assembled under the standard of the Prophet. It consisted of men from Madinah, from Makkah and from most of the tribes which had accepted Islam. One source had placed the strength of this army at 30,000 warriors, including 10,000 cavalry, but this is probably an exaggeration.
On arrival at Tabuk the Muslims came to know that the Roman elements in Jordan had withdrawn to Damascus. There was no need to go further. But the Prophet decided to subdue the tribes living in this region and bring them under the political control of Islam. The important places in the region were Eila (near the present-day Aqaba), Jarba, Azruh and Maqna-all lying along the Gulf of Aqaba. (See map below) Pacts were made with these tribes and they all agreed to pay the Jizya.1
One important region which the Prophet wished to subdue was a little farther away from Tabuk. This was Daumat-ul-Jandal (the present-day Al Jauf), ruled by Ukaidar bin Abdul Malik, a Christian prince from the tribe of Kinda who was famous for his love of hunting. To subdue this region, the Prophet sent Khalid with 400 horsemen and instructions to capture Ukaidar. "You will probably find him hunting the wild bull", said the Prophet.2
1. A tax levied on non-Muslims. In return they were exempt from military service and their safety was guaranteed by the Muslim State.