:salam2:
As I read, He was a Companion of Prophet Muhammad 
, lived 120 years. First 60 years as a non-believer and after embracing Islam, he lived for 60 years as a believer. He also was a great poet and wrote many poetry in defence of Prophet Muhammad . Some Muslims thinks because of his poetry, listening of music is permissible.
My question is not about listening music because we discussed this topic many many times, but I would like to know that:
1- Whether 'Hassan Bin Thaabit r.a., was only poet or musician too?
2- Whether He wrote poetry before embracing Islam or after that?
3- He wrote poetry during the time of Prophet Muhammad or after Him
Please share if you have any information. Kindly note again my topic is not about “listening Music” but about "Hassan Bin Thaabit r.a."
