Is Iblees a Jinn or an Angel?
Question

Was Iblis one of the angels or one of the jinn? And are the jinn from among the angels?
Praise be to Allah.Shaykh Muhammad al-Ameen al-Shanqeeti (may Allah be pleased with him) said: 
Allah says in the following ayah/verse (interpretation of the meaning): 
“He [Iblis] was one of the jinn; he disobeyed the command of his Lord.” [18:50] 
The apparent meaning is that the reason for his disobedience of his Lord was the fact that he was one of the jinn. The conjunction fa in the Arabic text [kana min al-jinn fa-fasaqa ‘an amri Rabbihi] is indicative of the reason, as in the Arabic phrase saraqa fa quti’at yaduhu which means, “he stole, so his hand was cut off”, i.e., that was because he stole; or the phrase saha fa sajada which means, “he forgot so he prostrated”, i.e., that was because he forgot. The same pattern is seen in the ayah (interpretation of the meaning): 
“And (as for) the male thief and the female thief, cut off [fa-qta’u] (from the wrist joint) their (right) hands.” [5:38] 
i.e., because of their stealing. 
Similarly, the phrase kana min al-jinn fa-fasaqa (he was one of the jinn [so] he disobeyed …) means that this was because he was in essence one of the jinn, because this feature is what made him different from the angels, for they obeyed the command but he disobeyed. Because of the apparent meaning of this ayah, a number of scholars were of the opinion that Iblis was not originally one of the angels, rather he was one of the jinn, but he used to worship Allah with them, so he was called by their name because he followed them, just as an ally of a tribe may be given their name. The dispute as to whether Iblis was originally an angel whom Allah changed into a devil, or whether he was not originally an angel but was included in the word malaikah (angels) because he had joined them and worshipped Allah with them, is a well known dispute among the scholars. The evidence of those who say that he was not originally one of the angels is based on two things: 
1 – The fact that angels are protected against committing kufr (disbelief) as was committed by Iblis, as Allah says (interpretation of the meaning): 
“Who disobey not, (from executing) the commands they receive from Allah, but do that which they are commanded.” [66:6] 
“They speak not until He has spoken, and they act on His Command.” [21:27] 
2 – Allah clearly states in 18:50 that he was one of the jinn, and the jinn are not angels. They said: this is a Quranic text concerning which there is some dispute.
Among those who stated that he was not originally one of the angels based on the apparent meaning of this ayah was-Hasan al-Basri, who was supported by al-Zamakhshari in his tafsir (exegesis). 
Al-Qurtubi said in his tafsir of Surat al-Baqarah: “The idea that he was one of the angels is the view of the majority, Ibn ‘Abbas, Ibn Mas’ud, Ibn Jurayj, Ibn al-Musayyib, Qutadah and others. It is the view chosen by al-Shaykh Abu’l-Hasan and regarded as more correct by al-Tabari, and it is the apparent meaning of the phrase “except Iblis.” [18:50] 
What the mufassirin (Quranic exegetists) have quoted from a group of the salaf (righteous predecessors), such as Ibn ‘Abbas and others, that he was one of the noblest of the angels, one of the keepers of Paradise, and that he controlled the affairs of the first heaven, and that his name was ‘Azazil is all taken from the Israliyyat (reports narrated from Jewish sources) and is not reliable. 
The clearest evidence concerning this matter, the evidence cited by those who said that he was not an angel because of the ayah (interpretation of the meaning): 
“He [Ibls] was one of the jinn; he disobeyed the command of his Lord,” [18:50] is the clearest text from the revelation that proves this point.
And Allah knows best.