From ziaraat.com newsletter - not sure I'll have time to write my own piece at this time....
Historical perspective of Eid-e-Mubahila
Najran was a fertile land located in the Northern mountainous region of Yemen about 20 Kms from Sanaa. About 40,000 Christians inhabited the land divided into 73 small towns. They were idol worshipers historically just like the Arabs but a priest named Femeon, a constructor by profession, preached Christianity in the area of Najran and soon all the population converted to Christianity and Najran became a powerful center of activities of Christians. They also constructed a church and named it 'Kaba-e-Najran'. They prayed and offered various offerings there which resulted in an annual income of about two hundred thousand Dinars which was used for the priest who lived and studied there.
After the conquest of Makkah when Islam started spreading rapidly and the warring groups came under the flag of Islam, the Holy Prophet(sawaw) starting sending emissaries to the tribes who had not yet accepted Islam. In 10 A.H. a similar message was sent to the Christians of Najran and they were offered either to accept the teachings of Islam or live in the protection of Muslims and give 'Jazia' - a kind of fee for protection services. When the Bishop of Najran received this message, he invited all the scholars and influential people of Najran and asked them to think and find a solution to this situation. This news spread rapidly among the masses and some people got infuriated as well but the Bishop of Najran pacified them and advised them to be mindful of the military might of the Islamic regime and try to find a peaceful solution.
Christian mission heads to Madina
After deliberations, it was finally decided to send a mission to Madina and have a dialog with the Muslims. A 14 member deligation headed by Aqib Saidawar and Abu Harisa started off for Makkah. Abu Harisa was considered as the greatest Bishop and scholar of the Christian world at that time and Aqib Saidawar was the biggest strategist and negotiator of the time. When the delegation reached Madina, the people got impressed by their lavish dressing and pomp and show since it was the first time that a mission had arrived in such a manner.
When they entered the Masjid-e-Nabawi, the Prophet Mohammad(sawaw) looked at the precious stones, gold and silk clothes that they were wearing and turned away his face and did not pay any attention to them. After a while when no one noticed their pomp and show, they got out of the Masjid-e-Nabawi and met Hazrat Usman and Ubaid-ur-Rehman outside and asked them as to why they were invited by the Muslims and then treated in this manner. Hazrat Usman mentioned that he did not have a clue about that but if they consult Imam Ali(a.s.), he would be able to tell them what was going on. They took the delegation with them and arrived at the house of Imam Ali(a.s.) and mentioned about the whole incidence to him. Imam Ali(a.s.) said to the delegation that they were wearing dresses of silk and ornaments of gold which depicted their superior mentality and that they should take them off and dress simply. Only then the Prophet(sawaw) would allow them to visit him and entertain them. When they followed the instructions of Imam Ali(a.s.), they were allowed to visit the Prophet Mohammad(sawaw) after the Prayers of Asar and have discussions with him.
Proposal of Mubahila
After exchange of views on several issues, the delegation did not seem to be willing to accept the observations about the incorrect beliefs of Christianity and the logical explanations proving the incorrectness of their beliefs. At that time Allah(swt) send down the famous Ayat-e-Mubahila of the Quran:
Glorious Quran Chapter 3 Verse 61:
And unto him who disputeth with thee therein after the knowledge hath come unto thee, Say ! ( O' Our Apostle Muhammad ! ) ( Unto them ) come ye, let us summon our sons, and ( ye summon ) your sons, and ( we summon ) our women and ( ye ) your women, and ( we summon ) ourselves and then let us invoke the curse of God on the liars !
Prophet Mohammad(sawaw) recited this Ayat and invited them for Mubahila - praying to God(swt) to destroy and banish the liars.
Mubahila became necessary since the Christian delegation was adamant to accept the truth. After some hesitations the delegations asked to be given one day to reconsider their options and then accepted to have the Mubahila after two days. In their consultations among themselves, the grand Bishop Abu Harisa told his companions that if tomorrow, Prophet Mohammad(sawaw) brings his companions and his tribesmen and military might with him for Mubahila then they should accept the challenge without fear but if he brings only the members of his family, then never accept the challenge.
Whom did the Prophet(sawaw) take with him
The Prophet Mohammad(sawaw) selected a place close to Madina for the Mubahila which was then cleaned and prepared by Hazrat Salman Farsi(r.a.) and the next day the Christian delegation reached the designated place. A number of muhajirren and ansaar also gathered at the site. The Holy Prophet Mohammad(sawaw) took with him Imam Hasan(a.s.), Imam Hussain(a.s.), Bibi Fatima(s.a.) and Imam Ali(a.s.) and headed towards the site in a manner that Prophet Mohammad(sawaw) was leading the group holding Imam Hasan(a.s.) and Imam Hussain(a.s.) and Bibi Fatima(s.a.) was behind him and Imam Ali(a.s.) was behind Bibi Fatima(s.a.).
Saad bin Abi Waqas relates that when the Ayat-e-Mubahila was sent down, Prophet Mohammad(sawaw) called Imam Ali(a.s.), Bibi Fatima(s.a.), Imam Hasan(a.s.) and Imam Hussain(a.s.) and said "O my Allah(swt), these are my Ahl-e-Bait" . (Sahih Muslim, Vol.2, Page 287).
Prophet Mohammad(sawaw) sat down under a tree with these weighty personalities and said that when I pray to God, you all should say 'Ameen'. When the Christian delegation saw a woman, two children and only one man with the Prophet(sawaw), they got scared and worried and Abu Harisa chanted "O my christian friends, I am seeing such bright faces that if they pray that God move this mountain from its place then the mountain will be moved. I warn you, do not have Mubahila with them or you all will be destroyed and banished."
The Christian delegation was still amazed and frightened when the brother of Abu Harisa, Karz ibn-e-Alqama stated that "O my fellows, it appears that Mohammad(sawaw) is the same last apostle and prophet that has been mentioned in our sacred books. We should not have Mubahila with them because anyone who had Mubahila with the prophets in the past as well was destroyed. Look around you and observe that the signs of your destruction are appearing." When they looked around, they observed that the entire atmosphere had changed and it appeared that a furious storm is in offing.
Result of the Mubahila
Witnessing this, they backed off from the contest and requested that their friendship be accepted. Prophet Mohammad(sawaw) accepted their request and asked Imam Ali(a.s.) to write the agreement according to which they Najran tribes accepted to pay 'Jazia' and live under the protection of the Muslims.