Gifts of Knowledge

Questioner: What is the ruling about entering a mosque with mobile phones that have ringtones, pictures and music?

Al-Fawzaan: That is not allowed, not in a mosque or elsewhere, but [doing so] is even more severe in a mosque, because it is obligatory to respect it, it is a place of worship and remembrance of Allaah سبحانه وتعالى, [a place of] prayer and recitation of the Quraan, and the Angels and Muslims assemble in it. So these wrong actions [munkaraat] are not permitted in it, not the ringtones, not the music and nor the pictures.

Al-Farq Bainan-Naseehah wat-Tajreeh, p. 39.