Banu Howazin was a tribe which inhabited the Turbah valley at two days march from Mecca. The tribe had indulged in some hostile activities against Islam, and in 629 A.D., the Holy Prophet decided to take punitive action against the tribe.
The Holy Prophet commissioned Umar to lead the expedition against Banu Howazin. The instructions of the Holy Prophet were that the tribe should be called to Islam, and in the event of their refusal, force should be used against them, and they should be driven away from the Turbah valley.
The Muslim expeditionary force consisted of thirty men. They had with them a guide of the Banu Hilal, who showed them the way, and led them to Turbah valley through unfrequented paths.
When the Muslim force reached the Turbah valley, they found that on hearing the approach of the Muslim force, the Banu Howazin had evacuated the valley and fled elsewhere with their animals and other belongings. The Muslim force stayed in the valley for some days. Scouts were sent in various directions to find some clue of the whereabouts of the Banu Howazin. No clue was found, and as the object of driving away the hostile tribe from the neighborhood of Mecca had been achieved without firing a shot, the Muslim force decided to return to Madina.
When on the return march, the Muslim force reached ZiAljaza, about six miles from Madina, the Banu Hilal guide said:
As on the expedition against Banu Howazin you have had no booty, and if you want to return to Madina carrying some booty I can guide you against some other tribe Banu Kbusham have been afflicted with famine. I have seen them going that way. If you think of attacking them and getting some booty, I can take you by a path to such a place from where you could launch a surprise attack on them. In spite of famine conditions they have ample wealth with them which you could appropriate."
Thereupon Umar said: "The Holy Prophet merely sent us against Banu Howazin, and the object was to promote the cause of Islam and not to get booty for ourselves. As the Holy Prophet did not authorize me to attack any other tribe, I am afraid I can not attack any other tribe just for the sake of booty, without the express instructions of the Holy Prophet. "When on return to Madina, Umar submitted his report to the Holy Prophet, and stated how he had not accepted the advice of the guide to attack Banu Khusham, the Holy Prophet said, "Umar you did well. If you had attacked them, I would have been unhappy."
After having been driven away from Madina, the Jews settled at Khyber. The Jews were a cunning and crafty people, and they involved themselves in intrigues against the Muslims.
The pact of Hudaibiya brought truce with the Quraish for a period of ten years. This meant that the Quraish could no longer openly aid the Jews against the Muslims. In spite of this situation, there was no diminution in the hostility of the Jews against the Muslims, and they began to work for the formation of an another coalition against the Muslims.
To forestall the evil designs of the Jews, the Holy Prophet marched to Khyber in 629 A.D. with a force of 1,400 Muslims. The Jews shut themselves in their forts. Some of these forts were very formidable with frowning walls built of the living rock.
The Jews had ample provisions, and there was no shortage of arms with them. They were offered to accept Islam, but they spurned the offer. Thereupon the Holy Prophet ordered an offensive against the Jews.
On the first day the Muslims led the attack against the Jews under the command of Abu Bakr. The Jews remained locked up in their forts and there was no confrontation.
The following day, Umar commanded the Muslim forces. The Jews remained shut up in their forts and there was no fight.
On the third day, Ali commanded the Muslim forces. Surprisingly, the Jews came out of their forts that day and fought in the open. In a hand to hand fight the Jews were overpowered and they capitulated.
According to the terms of the settlement, the Jews agreed to submit to the suzerainty of the Muslims, and to pay them a land tax equivalent to one half of the land produce.
The battle of Khyber had far reaching consequences. It established the paramountcy of Islam in the Arabian peninsula. The Jews now became the subjects of the Muslim State. As the Quraish thereby lost the support of the Jews, the battle of Khyber paved the way for the conquest of Mecca.
At Khyber, Zainab bint Harith a Jewish lady invited the Holy Prophet and his companions to a feast. Abu Bakr sat by the side of the Holy Prophet, and next to Abu Bakr sat Umar.
The Holy Prophet took a morsel of meat and after chewing it threw it away saying, "The meat is poisoned." Abu Bakr and Umar had so far held their hands. Bishr bin Bra who sat next to the Holy Prophet on the other side ate a good deal of meat, and after a few moments he was dead.
The feast ended in confusion, Zainab was put to explanation, and she admitted her guilt. She pleaded that she had poisoned the meat thinking that if Muhammad (peace be on him) was a prophet he would find that it was poisoned, and if he was not a prophet, the world would get rid of him.
Accounts of subsequent proceedings differ. According to one account Zainab became a Muslim and was forgiven.
According to another account she was beheaded.
A tradition has come down to us on the authority of Umar himself that on the day of Khyber some of the companions of the Holy Prophet stated that so and so were martyrs. When they came to a man about whom they said, "So and so is a martyr" the Holy Prophet declared, "By no means, I have seen him in hell in a cloak which he took dishonestly." The Holy Prophet said to Umar "Go, ibn al-Khattab and announce among the people three times that only the believers will enter Paradise." In compliance with these instructions Umar went out and announced three times, "Only the believers will enter Paradise."