Translation of the verse 50 from Surah Al-Kahf : Number of verses 110 - - page 299 - Part 15.
And (remember) when We said to the angels; "Prostrate to Adam." So they prostrated except Iblis (Satan). He was one of the jinns; he disobeyed the Command of his Lord. Will you then take him (Iblis) and his offspring as protectors and helpers rather than Me while they are enemies to you? What an evil is the exchange for the Zalimun (polytheists, and wrong-doers, etc).
And [mention] when We said to the angels, "Prostrate to Adam," and they prostrated, except for Iblees. He was of the jinn and departed from the command of his Lord. Then will you take him and his descendants as allies other than Me while they are enemies to you? Wretched it is for the wrongdoers as an exchange.
(18:50) Remember! When We said to the angels, "Bow down before Adam". They bowed down but Iblis did not. *47 He was one of the jinns, so he chose the way of disobedience to his Lord's Command. *48 What, would you then discard Me and make him and his offspring your patrons, though they are your enemies? What a bad substitute it is that these workers of iniquity are taking !
*47) The reference to the story of Adam and Iblis has been made here to warn the erring people of their folly. It is an obvious folly that people should discard their Prophets, who were their well-wishers, and get entangled in the snare set by their eternal enemy, Iblis, who has been jealous of man ever since he refused to bow down before Adam and became accursed.
*48) It was possible for Iblis to disobey Allah because he was not one of the angels but one of the jinns. It must be noted that the Qur'an is very explicit that the angels are inherently obedient:
(1) "They do not show arrogance; they fear their Lord Who is above them, and do whatever they are bidden." (XVI: 50)
(2) "..... They do not disobey the Command that is given to them by their Lord and do whatever they are bidden to do." (LXVI: 6)
In contrast to the angels, the jinns have been, like human beings, given the option to obey or not to obey. Therefore they have been given the power to believe or disbelieve, to obey or not to obey. This thing has been made explicit here by saying that Iblis was one of the jinns, so he deliberately chose the way of disobedience. Incidentally, this verse removes all those misunderstandings that are generally found among the common people that Iblis was one of the angels and not an ordinary angel but the instructor of the angels. As regards the difficulty that arises because of this statement of the Qur'an, "When We said to the angels, `Bow down before Adam. They bowed down but Iblis did not'," it should be noted that the Command to the angels was meant for all those on the Earth who were under the administration of the angels so that they should also be made submissive to man. Accordingly all these creatures bowed along with the angels but Iblis refused to bow down along with them.