It is narrated from Sayyiduna Shaddad, the father of al-Mustawrid (may Allah be pleased with him); he said: I came to the Messenger of Allah (peace and blessings be upon him) and took hold of his (peace and blessings be upon him) hand, and it was "softer than silk and colder than snow".
Hadith Referenceالمعجم الكبير للطبراني / باب الشين / 7079