Fath al-Rabbani

It is narrated from Ibn Mas'ud (may Allah be pleased with him) that two representatives, 'Aqib and Sayyid, from the ruler of Najran came; they wanted to engage in mutual imprecation (mubahala) with the Messenger of Allah (peace and blessings be upon him). But one of them said to the other: Do not engage in mubahala with this Muhammad (peace and blessings be upon him). By Allah! If he is a true Prophet and we engage in mubahala with him, then neither will we prosper nor will our descendants after us ever prosper. They presented themselves before the Messenger of Allah (peace and blessings be upon him) and said: We will not engage in mubahala with you; however, we will fulfill your demand. Send with us a trustworthy man so that we may pay him the agreed-upon wealth according to the peace treaty. The Noble Prophet (peace and blessings be upon him) said: I will send with you a man who is truly trustworthy and honest. Upon hearing this, all the Companions raised their eyes towards the Messenger of Allah (peace and blessings be upon him) (to see who would be granted this honor). Then the Prophet (peace and blessings be upon him) said: Abu 'Ubaydah! Stand up. When Sayyiduna Abu 'Ubaydah (may Allah be pleased with him) set out with them, the Noble Prophet (peace and blessings be upon him) said: This Abu 'Ubaydah (may Allah be pleased with him) is the trustworthy and reliable man of this Ummah. Sayyiduna Hudhayfah bin Yaman (may Allah be pleased with him) also narrated a similar hadith from the Noble Prophet (peace and blessings be upon him).