Musnad Ahmad 33:621

Musa narrated to us, Ibn Lahi'ah narrated to us, from Abu al-Zubayr, from Jabir, that a monk from al-Sham gifted the Messenger of Allah, may Allah bless him and grant him peace, a jubbah (outer garment) made of silk (sundus). The Prophet, may Allah bless him and grant him peace, wore it, then he came to the house and took it off. He was informed of a delegation coming to him, so Umar ibn al-Khattab ordered him to wear the jubbah for the arrival of the delegation. The Prophet, may Allah bless him and grant him peace, said: "It is not appropriate for us to wear it in the world, and it is appropriate for us to wear it in the Hereafter, but take it, O Umar." He (Umar) said: "Do you dislike it, yet I take it?" The Prophet, may Allah bless him and grant him peace, said: "I did not order you to wear it, but you may send it to the land of Persia, so you may obtain wealth through it." Umar refused, so the Prophet, may Allah bless him and grant him peace, sent it to the Negus, for he had been kind to those of the companions of Muhammad, may Allah bless him and grant him peace, who had fled to him.