Sunan At-Tirmidhi

Narrated Suwaid bin Ghafalah: That 'Umar gave a Khutbah at Al-Jabiyah and he said: ""The Messenger of Allah (ﷺ) prohibited silk except for two finger's worth of space, or three, or four."" [Abu 'Eisa said:] This Hadith is Hasan Sahih