What is the Shar'i evidence for the prohibition of music, and is it permissible to repeat the lyrics of songs for someone who hears them incidentally without intending to listen?

There should be no doubt about the prohibition of singing accompanied by musical instruments or that which contains obscenity. As for repeating permissible or good song lyrics, there is no harm in it, though it is better to avoid it, whereas obscene lyrics or those accompanied by forbidden musical instruments are prohibited. If one finds himself in a place where forbidden singing is present, he should leave it, and if he cannot, he should occupy himself with remembrance [of God] or other things.