A delegation of Christians headed by al-‘Aqib and Abu al-Harith started off for Makkah. Abu al-Harith was regarded as the greatest Bishop and scholar of the Christian world of the time and al-‘Aqib was the biggest strategist and negotiator of the time.
When the delegation reached Madina, the people were impressed by their lavish dressing and pomp and show since it was the first time that a delegation had arrived in such a manner.
When they entered the Masjid al-Nabawi, the Prophet Mohammad (PBUH) 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 left the mosque and met Uthman b. ‘Affan and ‘Abd-ur-Rahman b. ‘Awf outside and asked them as to why they were invited by the Muslims and then treated in this manner.
Uthman suggested that they consult Imam Ali (PBUH). When the delegation came to Imam Ali (PBUH) he told them that they were wearing dresses of silk and ornaments of gold which depicted their pride and that they should take them off and dress simply.
Only then would the Prophet (PBUH) allow them to visit him and entertain them. When they followed the instructions of Imam Ali (PBUH), they were allowed to visit the Prophet Mohammad (PBUH) after the prayers of ‘Asr and have discussions with him.
In the al-Tafsir of ‘Ali bin Ibrahim al-Qummi it is narrated from Imam al-Sadiq (PBUH):
'The Christians of Najran came (as a delegation) to the Messenger of Allah.... they rang the hand-bells and prayed; the Prophet's companions objected: “O Messenger of Allah! This in your mosque”? He (S) said: “Leave them (to pray as they like)”.
When they finished, they came to the Prophet (PBUH) and said: “To what do you call”? He (PBHU) said: “To bear witness that there is no God but Allah and that I am the Messenger of Allah and that 'Isa (Jesus) (a.s) is created a slave (of Allah), and he used to eat, drink and relieve himself”.
They said: “Then who was his father”? The revelation was then revealed to the Messenger of Allah (S) saying: “Say to them - what do you say about Adam, was he a created slave (of Allah), who would eat, drink, relieve himself and cohabit”? So the Prophet (S) asked them and they replied: “Yes”. He (S) asked them: “Then who was his father”? They could not answer, so Allah revealed:
Verily, the similitude of Jesus with Allah is as the similitude of Adam; Allah created him out of dust, then said to him, ‘Be’, and he became (3:59)
till the verse:
And should anyone argue with you concerning him, after the knowledge that has come to you…. and call down Allah’s curse upon the liars. (3:61)
The Messenger of Allah (S) said: “So challenge me: if I am telling the truth the curse falls on you, and if I am a liar the curse falls on me”. They said: “You have been just”.
They agreed on a date for ‘mubahala’ (mutual imprecation). [The term 'Mubahala' is derived from its Arabic root 'bahlah' meaning 'curse'. Thus the act of al-Mubahala means that each of the two parties invokes the curse of Allah on the other if the latter is untruthful].
When they returned to the places they were staying in, their leaders al-Sayyid, al-'Aqib and al-Ahtam said: “If he challenges us with his people, we accept the challenge for he is not a Prophet; but if he challenges us with his family in particular we don't challenge him, for he is not going to put forward his family unless he is truthful”.
In the morning, they came to the Messenger of Allah, and there with him were the Commander of the Faithful (Ali a.s), Fatimah, al-Hasan and al-Husayn (PBUH), so the Christians said: “Who are those”? The people replied: “This is his cousin and successor and son-in-law, and this is his daughter Fatimah, and these are his grandsons, al-Hasan and al-Husayn”.
When the Christian delegation saw a woman, two children and only one man with the Prophet (PBUH), they were frightened and worried and said to the Messenger of Allah (PBUH): “We will pay you whatever pleases you so excuse us from the ‘mubahala’”. Then the Messenger of Allah (S) made a settlement with them for them to pay the Jizya and they left.’