Sahih Bukhari Volume 8, Book 80, Hadith Number 762.

Narrated By ‘Aisha : Once Allah’s Apostle entered upon me and he was in a very happy mood and said, “O ‘Aisha: Don’t you know that Mujazziz Al-Mudliji entered and saw Usama and Zaid with a velvet covering on them and their heads were covered while their feet were uncovered. He said, ‘These feet belong to each other.”