Angels are very noble and delicate creatures and of high and numerous virtues (which have been expressed by the Quran). One of their traits is that they lack any materialistic and animalistic characteristics. They neither have any desire to sin, nor the strength to do so, making them pure of all sin.
Now, if infallibility only means for one not to sin, then one can say that the angels are infallible, because they are pure of all sin. But if infallibility means a special state and quality in which is granted by Allah to the prophets and imams, which protects one who is of human characteristics such as anger and lust and is able to commit sins, from committing them with his/her own will and choice, then one can no longer say that the angels are infallible.
Angels are extremely noble and delicate creatures who are pure of any sin. The Quran has considered them of very high ranks, and has even counted believing in them in the same level as believing in Allah (swt) and his messengers and their divine books.
The Noble Quran and Islamic tradition describe them like this:
1- Angels are intelligent creatures and honorable servants of Allah (swt).
2- "They do not venture to speak ahead of Him, and they act by His command"
3- They are continuously praising the Almighty Lord: "…while the angels continuously hymn the praise of their Lord and ask forgiveness for those on the earth.”
4- All of the angels prostrated because of the creation of Adam (as) and he became their teacher. This shows that man has the potential to perfect more than angels and in this sense, is higher than them.
5- They don't get married, nor eat or drink, as a hadith from Imam Sadiq says: "The angels don't eat, drink or get married, they stay alive by the breeze coming from Allah's arsh (divine throne)."
6- They neither sleep nor weaken, and never forget anything, as Imam Ali (as) says: "They don't have any feebleness, nor carelessness, nor sin…they never get sleepy, and never suffer from forgetfulness, their bodies never become weak, and they aren't in the womb of mothers and the backs of fathers (they don't get born)."
7- They have various ranks; some are always bowing (to Allah), while others are continuously prostrating. "There is none of us but he has an acknowledged status; We are drawn up in ranks; We are those who glorify [God]"
The question is, are these noble and delicate creatures infallible too? In order to answer this question, we need a definite definition for infallibility. Infallibility literally means “protection” and “blocking”, and is used for a spiritual quality in an individual that protects him/her from sin, forgetfulness, and mistake.
Therefore, infallibility is a spiritual quality granted by Allah (swt) to His prophets and imams. This doesn't mean that infallible individuals can't sin, it means that although they are completely capable of sinning, they still choose not to.
Just like a doctor of medicine who for instance knows that a certain material is poisonous and never gets near it, the infallibles' awareness of the reasons behind Islamic rulings causes them to stay away from sin.
One must remember that infallibility is a special gift from Allah to those who are able to accept its heavy responsibilities such as leading nations. Therefore, infallibility benefits all, and its advantages aren't limited to only the individual possessing it.
Taken into consideration the meaning of infallibility, one can conclude that although the angels are pure of all sins, yet they aren't infallible (as the prophets and imams are).
Of course, if we expand the meaning of infallibility to mean not committing sins, even if it is because one doesn't have the ability to, then the angels will also be infallible, because they don't have any desire to do so, on the contrary, they are always praising and sanctifying Allah (swt).
What must be noted is that all angels aren't of the same rank. The Quran says: "There is none of us but he has an acknowledged status."
Archangels like Jibra'il, Mika'il, Israfil, and Izra'il are all very high angels that are very close to Allah (swt), to the extent that philosophers refer to them as "the heads of all angels". Others are of lower levels, each having their own responsibilities and duties. Imam Ali (as) explains their levels and ranks like this: "Among them are those who work as trusted bearers of His message and carry it to His prophets. Among them are the protectors of His creatures and guards of the doors of the gardens of
As for the hadiths that speak of some angels disobeying Allah (swt) and being punished as a result, all scholars don't accept them and they aren’t that definite. Hadiths like the story of "Futrus" and other angels. Some believe that the story of Futrus needs to be proven, because Futrus is a Greek word and he hasn't been called an angel in the supplication of the third of the month of Sha'ban where he has been named in. All that has been said there is that Futrus seeked refuge in Imam Husain's cradle, in addition to the fact that this supplication's authenticity itself needs to be analyzed…
Others hesitate to accept the disobedience of angels saying: "The story of Futrus is in contradiction with the verse that says: "They say," The All-beneficent has taken offsprings." Immaculate is He! Rather they (the angels) are (His) honored servants".
Therefore, this group of scholars solve the problem by saying that angels cannot disobey Allah (swt).
On the other hand, Shia scholars say that even if we consider all of these hadiths as authentic, there are still several possibilities that can solve the problem:
1- Some interpreters of the Quran say that angels are punished as a result of "failing to do the better" (tarkul-awla), not disobedience. This can mean that in the process of fulfilling their responsibilities, they leave something of higher importance and do something less important. Or it can mean that instead of getting the job done in a better situation and time, they leave it for a time that doesn’t suit best, not that they don’t do it at all.
2- Some say that these types of hadith are related to a certain group of angels that are similar to humans: "Some angels have been referred to as "earthly angels", they are invisible creatures, yet maybe very similar to humans; meaning that they also have rulings (like the Islamic ones that pertain to us) and sometimes disobey their lord. Their essence isn’t clear to us…it has also been said in some traditions that some angels have even been created by earthly elements.
3- Some believe that if both the authenticity of these hadiths are proven and that Futrus was truly an angel, there still is no contradiction between them and the verse that says that they don’t disobey Allah (swt), because all angels aren’t the same; those of them who carry the divine throne and those who carry revelation, are of very high degrees: "There is none of us but has an acknowledged status." Those who deliver revelation are infallible and have no perfection. There is no reason to consider all of them of the same category, and not have any whom, like humans, possess the potential of perfecting. So it is possible to have an "earthly" angel named Futrus that differs from heavenly or hereafter angels.
Considering what was quoted from Imam Ali (as), if what he said was a description of the essence of angels, then all angels will be sinless no matter what type or rank; of course, they might sometimes fail to do the better as was said before. But if what he was expressing was a description of a specific group of angels given the context of this hadith, then there is no other choice but to explain it using one of the possibilities mentioned above.
Anyway, since angels aren’t materialistic, the only way to truly get familiar with them is by seeing what the Quran says about them, and all hadiths aren’t dependable in this field; they must be analyzed to make sure that they are authentic and till then, the Quran is our only reference.
Baqarah:285. “The Messenger believes in what has come down to him from his Creator and Nurturer and so do the believers; all of them believe In Allah, in His Angels, in His Books and in His Messengers”
Anbiya’:26. "بَلْ عِبادٌ مُکْرَمُونَ".
Anbiya’:27. لا یَسْبِقُونَهُ بِالْقَوْلِ وَ هُمْ بِأَمْرِهِ یَعْمَلُونَ Tahrim:6
Shura:5. وَ الْمَلائِکَةُ یُسَبِّحُونَ بِحَمْدِ رَبِّهِمْ وَ یَسْتَغْفِرُونَ لِمَنْ فِی الْأَرْضِ
 Biharul-Anwar, v.59, pg. 174, hadith 4: "ان الملائکة لا یاکلون و لا یشربون و لا ینکحون و انما یعیشون بنسیم العرش".
Biharul-Anwar, v.59, pg. 175. "لیس فیهم فترة، و لا عندهم غفلة، و لا فیهم معصیة ... لا یغشاهم نوم العیون و لا سهوا العقول، و لا فترة الأبدان، لم یسکنوا الاصلاب و لم تضمهم الارحام"
Saffat:164-166: "ما مِنَّا إِلَّا لَهُ مَقامٌ مَعْلُومٌ وَ إِنَّا لَنَحْنُ الصَّافُّونَ وَ إِنَّا لَنَحْنُ الْمُسَبِّحُونَ"
Muhammad Taqi Misbah Yazdi, Usule Aqa’ed, v.2, pg. 121.
Tafsir Nemouneh, v.17, pg. 305.
Nahjul-Balaghah of Feydhul-Islam, Khutba (sermon) 1.
Porsesh-ha va Pasokh-ha dar Mahzare Ayatullah Javadi Amoli, v.2, pg. 88.
Anbiya’:26. "وَ قالُوا اتَّخَذَ الرَّحْمنُ وَلَدًا سُبْحانَهُ بَلْ عِبادٌ مُکْرَمُونَ"
Tahrim:6 "یا أَیُّهَا الَّذینَ آمَنُوا قُوا أَنْفُسَکُمْ وَ أَهْلیکُمْ نارًا وَقُودُهَا النّاسُ وَ الْحِجارَةُ عَلَیْها مَلائِکَةٌ غِلاظٌ شِدادٌ لا یَعْصُونَ اللّهَ ما أَمَرَهُمْ وَ یَفْعَلُونَ ما یُؤْمَرُونَ"
(O you who have faith! Save yourselves and your families from a fire whose fuel is people and stones, over which are [assigned] angels, severe and mighty, who do not disobey whatever Allah has commanded them, and carry out what they are commanded)
Ayatullah Makarem Shirazi in a question and answer session in his presence.
Murtadha Mutahhari, Tawhid, pg. 342.
Tahrim:6 “ "یا أَیُّهَا الَّذینَ آمَنُوا قُوا أَنْفُسَکُمْ وَ أَهْلیکُمْ نارًا وَقُودُهَا النّاسُ وَ الْحِجارَةُ عَلَیْها مَلائِکَةٌ غِلاظٌ شِدادٌ لا یَعْصُونَ اللّهَ ما أَمَرَهُمْ وَ یَفْعَلُونَ ما یُؤْمَرُونَ
Towsiyeha, Porsesh-ha va Pasokh-ha dar Mahzare Ayatullah Javadi Amoli, v.2, pg. 88-89.
See the article “Pajooheshi dar Revayate Futruse Malek” by Muhammad EhasaniFar, pp.68-80, Ulume Hadith Magazine, no. 34 (year 9, issue 4, winter of 1383) regarding this issue. In this article, he considers the hadiths of the story of Futrus authentic, saying that what Futrus did wasn’t true disobedience, but only something like “failing to do the better” which is in no way in contradiction with their infallibility.