To wear the best clothes (for the Jumu'ah prayer)

Narrated Umar bin Al-Khattab: I 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 Messenger (ﷺ) 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 Messenger (ﷺ) and he gave one of them to `Umar bin Al-Khattab. On that `Umar said, "O Allah's Messenger (ﷺ)! 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 Messenger (ﷺ) 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.