Called Najashi in Arabic was the king of Ethiopia in the days of Muhammad. It was he who gave shelter and protection to the early followers of Muhammad who escaped Mecca's Quraysh.

Sahih Muslim HadithHadith 4382        Narrated byAnas ibn Malik
The Prophet of Allah (peace be upon him) wrote to Chosroes (King of Persia), Caesar (Emperor of Rome), Negus (King of Abyssinia) and every (other) despot inviting them to Allah, the Exalted. And this Negus was not the one for whom the Messenger of Allah (peace be upon him) had said the funeral prayers.

Sahih Al-Bukhari HadithHadith 5.216        Narrated byAbu Musa
We received the news of the departure of the Prophet (to Medina) while we were in Yemen. So we went on board a ship but our ship took us away to An-Najashi (the Negus) in Ethiopia. There we met Ja'far bin Abi Talib and stayed with him till we came (to Medina) by the time when the Prophet had conquered Khaibar. The Prophet said, "O you people of the ship! You will have (the reward of) two migrations."

Sahih Al-Bukhari HadithHadith 5.219        Narrated byJabir bin Abdullah
The Prophet offered the funeral prayer for Ashama, the Negus, with four Takbir.

Sahih Al-Bukhari HadithHadith 5.220        Narrated byAbu Huraira
that Allah's Apostle informed them (i.e. his companions) of the death of Negus, the king of Ethiopia, on the very day on which the latter died, and said, "Ask Allah's forgiveness for your brother." Abu Huraira further said, "Allah's Apostle made them (i.e. the Muslims) stand in rows at the Musalla (i.e. praying place) and led the funeral prayer for the Negus and said four Takbir."

Sunan of Abu-DawoodHadith 155        Narrated byAbuMusa al-Ash'ari
Negus presented to the Messenger of Allah (peace be upon him) two black and simple socks. He put them on; then he performed ablution and wiped over them.

Al-Tirmidhi HadithHadith 4418        Narrated byBuraydah ibn al-Hasib
The Negus presented the Prophet with two plain black shoes and he wore them.
Ibn Majah transmitted it, and Tirmidhi added that he then performed ablution and wiped over them.

Sunan of Abu-DawoodHadith 2102        Narrated byUmm Habibah
Urwah reported on the authority of Umm Habibah that she was married to Abdullah ibn Jahsh who died in Abyssinia, so the Negus married her to the Prophet (peace be upon him) giving her on his behalf a dower of four thousand (dirhams). He sent her to the Apostle of Allah (peace be upon him) with Shurahbil ibn Hasanah. AbuDawud said: Hasanah is his mother.

Sunan of Abu-DawoodHadith 2103        Narrated byUmm Habibah daughter of AbuSufyan
Az-Zuhri said: The Negus married Umm Habibah daughter of AbuSufyan to the Apostle of Allah (peace be upon him) for a dower of four thousand dirhams. He wrote it to the Apostle of Allah (peace be upon him) who accepted it.

Sahih Muslim HadithHadith 2083        Narrated byImran ibn Husayn
Allah's Messenger (peace be upon him) said: A brother of yours has died; so stand up and offer prayer for him, i.e. Negus. And in the hadith transmitted by Zubayr (the words are): Your brother.

       *** It is very illuminating about the character of Muhammad, who was supported by both the Christians and the Jews in his early struggle gainst the  pagan Quraysh, a support that allowed him to survive.

        In return, to show his gratitude, he attacked, despoiled, plundered, murdered and exiled many of them in his lust for plunder and power ***