Sahih Muslim
The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fadail Al-Sahabah)
Book Number: 031 / Hadith Number: 6036
Al-Bara' reported that a garment of silk was presented to Allah's Messenger (may peace be upon him). His Companions touched it and admired its softness; there- upon he said: Do you admire the softness of this (cloth)? The handkerchiefs of Sa'd b. Mu'adh in Paradise are better than this.