Did Al-Najashi convert to Islam during the Prophet’s lifetime and which book mentions it?

Al-jawab billahi at-taufeeq (the answer with Allah’s guidance)

Yes, Al Najjashi (Negus-the king of Abyssinia (Ethiopia)) reverted to Islam during the life of the prophet (Sallallahu Alaihi Wasallam).

Below, is an extract from Ar Raheequl Makhtum Pg. 221,222 (The sealed nectar-Biography of the noble prophet (Sallallahu Alaihi Wasallam):

“Negus, king of Abyssinia (Ethiopia), his name was Ashama bin Al-Abjar, received the Prophet’s message, despatched by Amr bin Omaiyah Ad-Damari, which At-Tabari
referred to, either late in the sixth year or early in the seventh year A.H. Deep scrutiny into the letter shows that it was not the one sent after Al-Hudaibiyah event. Wording of the letter rather indicates that it was sent to that king when Ja‘far and his companions emigrated to Abyssinia (Ethiopia) during the Makkan period. One of its sentences read “I have despatched my cousin, Ja‘far with a group of Muslims, to you. Do be generous towards them and give up haughtiness.” Al-Baihaqi, on the authority of Ibn Ishaq, gave the following narration of the
Prophet’s letter sent to Negus:

“This letter is sent from Muhammad, the Prophet to Negus Al-Ashama, the king of Abyssinia (Ethiopia).

Peace be upon him who follows true guidance and believes in Allâh and His Messenger. I bear witness that there is no god but Allâh Alone with no associate, He has taken neither a wife nor a son, and that Muhammad is His slave and Messenger. I call you unto the fold of Islam; if you embrace Islam, you will find safety, “Say (O Muhammad [pbuh]): ‘O people of the Scripture (Jews and Christians), come to a word that is just between us and you, that we worship none but Allâh, and that we associate no partners with Him, and that none of us shall take others as lords besides Allâh.’ Then, if they turn away, say: ‘Bear witness that we are Muslims.’ ” [Al-Qur’an 3:64]
Should you reject this invitation, then you will be held responsible for all the evils of the Christians of your people.”

Dr. Hameedullah (Paris), a reliable verifier, has adduced a version of the above letter
disclosed only a short time ago and identical to Ibn Al-Qaiyim’s narration. Dr. Hameedullah exerted painstaking effort and used all means of modern technology to verify the text of the letter, which reads as follows:

“In the Name of Allâh, the Most Beneficent, the Most Merciful.
From Muhammad the Messenger of Allâh to Negus, king of Abyssinia (Ethiopia). Peace be upon him who follows true guidance. Salutations, I entertain Allâh’s praise, there is no god but He, the Sovereign, the Holy, the Source of peace, the Giver of peace, the Guardian of faith, the Preserver of safety. I bear witness that Jesus, the son of Mary, is the spirit of Allâh and His Word which He cast into Mary, the virgin, the good, the pure, so that she conceived Jesus. Allâh created him from His spirit and His breathing as He created Adam by His Hand. I call you to Allâh Alone with no associate and to His obedience and to follow me and to believe in that which came to me, for I am the Messenger of Allâh. I invite you and your men to Allâh, the Glorious, the All-Mighty. I hereby bear witness that I have communicated my message and advice. I invite you to listen and accept my advice. Peace be upon him
who follows true guidance.”[Za’d Al-Ma’ad 3/60]

The text of this letter is doubtlessly authentic, but to maintain that it was written after Al- Hudaibiyah event is still a question lacking in definite evidence. When ‘Amr bin Omaiyah Ad-Damari communicated the Apostolic letter to Negus, the latter took the parchment and placed it on his eye, descended to the floor, confessed his faith in Islam and wrote the following reply to the Prophet [pbuh]:

“In the Name of Allâh, the Most Beneficent, the Most Merciful.
From Negus Ashama to Muhammad, the Messenger of Allâh. Peace be upon you, O Messenger of Allâh! and mercy and blessing from Allâh beside Whom there is no god. I have received your letter in which you have mentioned about Jesus and by the Lord of heaven and earth, Jesus is not more than what you say. We fully acknowledge that with which you have been sent to us and we have entertained your cousin and his companions. I bear witness that you are the Messenger of Allâh, true and confirming (those who have gone before you), I pledge to you through your cousin and surrender myself through him to the Lord of the worlds.”[Za’d Al-Ma’ad 3/61]

The Prophet [pbuh] had asked Negus to send Ja‘far and his companions, the emigrants to Abyssinia (Ethiopia), back home. They came back to see the Prophet [pbuh] in Khaibar. Negus later died in Rajab 9 A.H. shortly after Tabuk Ghazwa. The Prophet [pbuh] announced his death and observed prayer in absentia for him. Another king succeeded Negus to the throne and another letter was sent to him by the Prophet [pbuh] but whether or not he embraced Islam is still a question not answered yet. [Sahih Muslim 2/99]

And Only Allah Ta’ala Knows Best.

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Moulana Qamruz Zaman
London, UK