Do the Devils Enter the Mosques?
Question

                Do the shayateen (devils) enter the mosques?
Praise be to Allah.
    There are proven reports in the sunnah (prophetic teachings) 
    which indicate that the devils do enter the mosques, because they go into 
    the gaps in the rows and whisper (waswas) to the individual when he is 
    praying so as to distract him and rob him of proper focus (khushoo‘).

    Abu Dawood and Ahmad narrated, in a report that was classed 
    as saheeh (authentic) by al-Albani in al-Mishkat, from Anas ibn Malik (may 
    Allah be pleased with him) that the Messenger of Allah (peace and blessings 
    of Allah be upon him) said: “Consolidate your rows, make them close together 
    and stand with your necks in line with one another, for by the One in Whose 
    hand is my soul, I see the devils going into the gaps in the rows as if they 
    are little lambs.” 

    Muslim narrated in his Saheeh from Abu’l-‘Ala that ‘Uthman 
    ibn Abi’l-‘As came to the Prophet (peace and blessings of Allah be upon him) 
    and said: O Messenger of Allah, the shaytan (devil) interferes between me 
    and my prayer and my recitation, and he makes me confused. The Messenger of 
    Allah (peace and blessings of Allah be upon him) said: “That is a devil 
    called Khinzab. If you feel that, then seek refuge with Allah from him and 
    spit dryly to your left three times.” He said: I did that and Allah took him 
    away from me. 

    Muslim also narrated that Abu’d-Darda (may Allah be pleased 
    with him) said: The Messenger of Allah (peace and blessings of Allah be upon 
    him) stood up (to pray) and we heard him saying: “I seek refuge with Allah 
    from you.” Then he said: “I curse you with the curse of Allah” three times, 
    and he stretched out his hand as if to take something. When he had finished 
    praying, we said: O Messenger of Allah, we heard you say something during 
    the prayer that we have not heard you say before, and we saw you stretch out 
    your hand. He said: “The enemy of Allah, Iblis, came with a brand of fire to 
    throw it in my face…” 

    Al-Bukhari, Muslim and others narrated from Abu Hurayrah (may 
    Allah be pleased with him) that the Messenger of Allah (peace and blessings 
    of Allah be upon him) said: “When the call to prayer is given, the shaytan 
    runs away breaking wind loudly so that he will not hear the call. Then when 
    the call has ended, he comes but when iqamah (final call before prayer) for 
    prayer is given he runs away, then when the iqamah has ended, he comes back 
    so that he can whisper to the individual, saying: Remember such and such, 
    remember such and such -- about things that he was not thinking about, until 
    he confuses the man and he does not know how many (rak‘ahs/units) he 
    prayed. 

    These hadeeths (narrations) and others clearly indicate that 
    the devils do enter the mosques, but when they hear the adhan they run away 
    to somewhere where they cannot hear the call, then they come back after that 
    and distract a person from his prayer and recitation. 

    And Allah knows best.