Musnad Abu Ya'la al-Mawsili 113:1

Ibrahim ibn al-Hajjaj al-Sami narrated to us, from Wuhayb, from Ayyub, from Abu Qilabah, from Anas: That the Prophet (peace be upon him) used to visit Umm Sulaym and take a midday nap (qaylulah) at her place. He would pray upon a leather mat (nat') and take a midday nap. He used to sweat profusely, so she would collect the sweat from the leather mat and put it into perfume bottles. And he used to pray upon the khumrah (a small mat made of palm leaves).