THE INVASION OF TABUK IN RAJAB, IN THE YEAR 9 A.H.
The invasion and the conquest of Makkah was considered a decisive one between the truth and the  error. As a result of which, the Arabs had no more doubt in Muhammad’s mission. Thus we see that  things went contrary to the pagans’ expectations. People started to embrace Islam, the religion of
Allâh,  in great numbers. This is manifested clearly in the chapter — The delegations, of this book. It can also  be deduced out of the enormous number of people who shared in the Hajjatul-Wadâ‘ (Farewell
Pilgrimage). All domestic troubles came to an end. Muslims, eventually felt at ease and started setting  up the teachings of Allâh’s Laws and intensifying the Call to Islam.
THE UNDERLYING REASONS:
The Byzantine power, which was considered the greatest military force on earth at that time, showed  an unjustifiable opposition towards Muslims. As we have already mentioned, their opposition started at  killing the ambassador of the Messenger of Allâh (peace be upon him), Al-Harith bin ‘Umair Al-Azdi, by
Sharhabeel bin ‘Amr Al-Ghassani. The ambassador was then carrying a message from the Prophet
(peace be upon him) to the ruler of Busra. We have also stated that the Prophet consequently  dispatched a brigade under the command of Zaid bin Haritha, who had a fierce fight against the
Byzantines at Mu’tah. Although Muslim forces could not have revenge on those haughty overproud  tyrants, the confrontation itself had a great impression on the Arabs, all over Arabia.
Caesar — who could neither ignore the great benefit thMu’tah Battle had brought to Muslims, nor  could  he disregard the Arab tribes’ expectations of independence, and their hopes of getting free from his  influence and reign, nor he could ignore their alliance to the Muslims — realizing all that, Caesar was  aware of the progressive danger threatening his borders, especially Ash-Sham-fronts which were  neighbouring Arab lands. So he concluded that demolition of the Muslims power had grown an urgent  necessity. This decision of his should, in his opinion, be achieved before the Muslims become too  powerful to conquer, and raise troubles and unrest in the adjacent Arab territories.
To meet these exigencies, Caesar mustered a huge army of the Byzantines and pro-Roman
Ghassanide  tribes to launch a decisive bloody battle against the Muslims.
General News about the Byzantines and Ghassanide Preparations for War.
No sooner news about the Byzantine’s preparations for a decisive invasion against Muslims reached
Madinah than fear spread among them. They started to envisage the Byzantine invasion in the least  sound they could hear. This could be clearly worked out of what had happened to ‘Umar bin
Al-Khattab  one day.
The Prophet (peace be upon him) had taken an oath to stay off his wives for a month in the ninth year  of Al-Hijra. Therefore, he deserted them and kept off in a private place. At the beginning, the
Companions of the Messenger of Allâh were puzzled and could not work out the reason for such  behaviour. They thought the Prophet (peace be upon him) had divorced them and that was why he  was  grieved, disturbed and upset. In ‘Umar’s version of the very story he says: “I used to have a Helper  friend who often informed me about what happened if I weren’t present, and in return I always  informed him of what had taken place during his absence. They both lived in the high part of Madinah.
Both of them used to call at the Prophet alternatively during that time of suspense. Then one day I  heard my friend, knock at the door saying: “Open up! Open up!” I asked wondering, “What’s the  matter? Has the Ghassanide come?” “No it is more serious than that. The Messenger of Allâh (peace  be  upon him) has deserted his wives.”
In another version, ‘Umar said, “We talked about Ghassanide preparations to invade us. When it was  his turn to convey the news to me, he went down and returned in the evening. He knocked at the door  violently and said ‘Is he sleeping?’ I was terrified but I went out to meet him. ‘Something serious had  taken place.’ He said. ‘Has the Ghassaindes arrived?’ Said I. ‘No,’ he said, ‘it is greater and more  serious. The Messenger of Allâh (peace be upon him) has divorced his wives.’”
This state of too much alertness manifests clearly the seriousness of the situation that Muslims began  to experience. The seriousness of the situation was confirmed to a large degree by the hypocrites  behaviour, when news about the Byzantines’ preparations reached Madinah. The fact that the
Messenger of Allâh (peace be upon him) won all the battles he fought, and that no power on earth  could make him terrified, and that he had always proved to be able to overcome all the obstacles that  stood in his way - did not prevent the hypocrites, who concealed evil in their hearts, from expecting