What is meant by "He cast upon them of His light" in the noble Hadith, and is this light created, or is it an uncreated attribute of Allah, and is "min" (from/of) in this context to be understood as indicating partiality?

The Hadith (definition) "Allah created His creation in darkness, then cast upon them some of His Light," was graded as hasan (definition) (good) by Tirmidhi and sahih (definition) (authentic) by Al-Albani. This Light is an attribute of Allah Almighty that never separates from Him. Therefore, casting the Light means illumination occurs without the attribute detaching.

Ibn Al-Qayyim said: Light is of four types: a Name of Allah, a light attributed to Him (like the light of His Face or His Essence), the Light of the heavens and the earth, and His veil of Light. The Light in the Hadith is the light of an attribute, like His life and His knowledge.

Light is one of Allah Almighty's magnificent attributes, and the earth will shine with His Light on the Day of Judgment. The dispute concerning the attribute of Light was with the Mu'tazilah.

Ibn Al-Qayyim affirmed that the Light of Allah Almighty differs from the light of creation (like the sun, moon, and lamps). The light of creation is created and exists within a created body, whereas the Light of Allah is an attribute of His Essence and His Supreme Face, and it is uncreated.

Sheikh Ibn Baz clarified that light is of two types: created light (such as the light of the sun and moon), which is from Allah's creation, and uncreated light, which is an attribute of Allah Almighty. Thus, the light of His Face and His Essence is uncreated and is an attribute of His, like His hearing and His sight.

In summary, the Light mentioned in the Hadith is the light of the attribute that subsists in Allah, and His illuminating something from His creation does not mean that the attribute separates from the One described or becomes fragmented.