The Prophet Muhammad صلى الله عليه وسلم is Light (Surah 5:15)

 بِسۡمِ اللّٰہِ الرَّحۡمٰنِ الرَّحِیۡمِ

الصلاة والسلام عليك يا سيدي يا رسول الله

In the Name of Allah, the Rahman, the Merciful

Blessings and salutations of peace be upon you my Master, Apostle of Allah

Allah, Holy and Exalted is He, says:

قَدۡ جَآءَکُمۡ مِّنَ اللّٰہِ نُوۡرٌ وَّکِتٰبٌ مُّبِیۡنٌ

There has come to you from Allah a Light and a clear Scripture

(Surah 5, Ayah 15)

In his commentary on this portion of the blessed Ayah, the great Mufassir, Ibn Jarir al-Tabari, says:

قد جاءكم يا أهل التوراة والإنـجيـل من الله نور يعنـي بـالنور مـحمداً صلى الله عليه وسلم الذي أنار الله به الـحقّ وأظهر به الإسلام ومـحق به الشرك فهو نور لـمن استنار به يبـين الـحقّ

O people of the Torah and the Gospel, there has come to you from Allah a light. By light he means Muhammad, may Allah bless him and grant him peace, through whom Allah illuminated the truth, made Islam manifest, and destroyed polytheism. He is a light for whoever is enlightened by him, clarifying the truth (Tafsir Ibn Jarir; v.8, p.264)

In another Ayah, Allah, Holy and Exalted is He, says about the Prophet Muhammad, sall Allahu alaihi wasallam:

وَّدَاعِیًا اِلَی اللّٰہِ بِاِذۡنِہٖ وَسِرَاجًا مُّنِیۡرًا

And as a summoner unto Allah by His command and as a light-giving lamp

(Surah 33, Ayah 46)

So it is established from the Nass of the Holy Quran that the Prophet Muhammad, sall Allahu alaihi wasallam, is a light and a lamp that is the source of light. One of the major controversies among Sunni Muslims is whether the Prophet, sall Allahu alaihi wasallam, being a light means he is literally made of light like the Angels. No one denies the figurative meaning of the Prophet being light, meaning one who guides toward and manifests the truth. I believe the Prophet Muhammad, peace be upon him, is literally nur. But the Arabic word nur, which is commonly translated into English as “light” is broader and more significant in meaning. Physical light is made of particles called photons. I do not say that the Prophet, peace be upon him, is a being whose substance is photons, but that he is certainly a being of nur whose complete reality we can’t comprehend. In a Hadith that is weak, Ibn Abbas, radi Allahu anhuma, narrates:

كَانَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ ‌أَفْلَجَ ‌الثَّنِيَّتَيْنِ ‌إِذَا ‌تَكَلَّمَ ‌رُئِيَ ‌كَالنُّورِ ‌يَخْرُجُ ‌مِنْ ‌بَيْنِ ‌ثَنَايَاهُ

The Apostle of Allah, may Allah bless him and grant him peace, had a gap in his front teeth. When he spoke, it was seen as if light was coming out from between his front teeth (Musnad al-Darimi; p.113, #63)

Therefore, while it is correct to affirm that the Prophet, peace be upon him, is literally nur “light” and not merely in the figurative sense of being a source of guidance and truth, this should never lead one to doubt or deny his humanity. Those who argue that the Prophet, peace be upon him, merely had the human form in the apparent but in reality he is light are incorrect. He is light in reality and he is human in reality, these two are not mutually exclusive in his case. And Allah and His Apostle know best!