Narrated ‘Abdullah bin ‘Umar:
Umar bin Al-Khattab saw a silken cloak (being sold) at the gate of the Mosque and said to Allah’s Apostle, “I wish you would buy this to wear on Fridays and also on occasions of the arrivals of the delegations.” Allah’s Apostle replied, “This will be worn by a person who will have no share (reward) in the Hereafter.” Later on similar cloaks were given to Allah’s Apostle and he gave one of them to ‘Umar bin Al-Khattab. On that ‘Umar said, “O Allah’s Apostle! You have given me this cloak although on the cloak of Atarid (a cloak merchant who was selling that silken cloak at the gate of the mosque) you passed such and such a remark.” Allah’s Apostle replied, “I have not given you this to wear”. And so ‘Umar bin Al-Khattab gave it to his pagan brother in Mecca to wear.
It’s haram (unlawful) for Muslim men to wear silk. To know how halal or haram original silk, part-silk, artificial silk etc. are, read this post at islamqa.com! You’ll find more related fatwas on this website as well.
It’s a profound statement:
This will be worn by a person who will have no share (reward) in the Hereafter.
Why do we then argue about it? Just because we think something is halal, doesn’t make it halal. Imagine being taken by surprise in the Hereafter, when you’re told that you don’t deserve any of the silken cloaks that the people of Paradise are donning, just because you wore that silken shirt at that party to look fab. Brothers, give up the worldly silk, to wear the best silk in Paradise. :)