Musnad Ahmad 32:1245

Sulayman ibn Dawud narrated to us, Shu'bah informed us, from Qatadah, from Anas, that the Prophet (peace and blessings of Allah be upon him) was brought a garment of silk. They began to touch it and look at it. He said: "Do you marvel at this? The handkerchiefs of Sa'd, or the handkerchief of Sa'd ibn Mu'adh in Paradise, are better than this, or softer than this."