Al-Wāqidī said: The Messenger of Allah ﷺ wrote: (1)

“In the name of Allah, the Most Compassionate, the Most Merciful.
From Muhammad, the Messenger of Allah, to the Negus, king of Abyssinia.
Peace be upon you. I praise before you Allah—there is no deity except Him—the Sovereign, the Most Holy, the Source of Peace, the Giver of Faith, the Overseer. I bear witness that Jesus son of Mary is the spirit of Allah and His word that He cast to Mary, the virgin, the good and chaste, and that she conceived Jesus. He created him from His spirit and His breath just as He created Adam with His own hand. I summon you to Allah alone, without partner, and to mutual loyalty in obeying Him; and I call upon you to follow me and believe in what has been revealed to me, for I am the Messenger of Allah sent to you. I further invite you and your troops to Allah. I have conveyed the message and offered you sincere counsel, so accept my advice. Peace be upon those who follow guidance.” (2)

The Negus wrote back to him:

“In the name of Allah, the Most Compassionate, the Most Merciful.
To Muhammad, the Messenger of Allah, from the Negus Aṣḥama.
Peace be upon you, O Prophet of Allah, and the mercy and blessings of Allah—the One besides whom there is no deity.
To proceed: Your letter has reached me concerning what you mentioned about Jesus. By the Lord of heaven and earth, Jesus does not exceed what you have stated by so much as a thufruq; he is exactly as you described. We have understood the mission for which you sent your cousin and his companions to us, and we have shown them favor. I testify that you are indeed the truthful, confirmed Messenger of Allah. I have pledged allegiance to you and to your cousin, and I have submitted, at his hand, to Allah, Lord of all realms.” (3)

A thufruq is the tiny ligament that joins the pit to the flesh of a date.