Musnad Ahmad 1153:2092

Uthman ibn Umar narrated to us, Yunus narrated to us, from al-Zuhri, from Urwah, from Aisha, that the Messenger of Allah (peace and blessings of Allah be upon him) used to pray on a *khumrah* (a small mat). He said: "O Aisha, remove this mat of yours from us, for I fear that it may tempt the people."