Sahih Muslim
The Book of Marriage (Kitab Al-Nikah)
Book Number: 008 / Hadith Number: 3440
'A'isha (Allah be pleased with her) reported: One day Allah's Apostle (may peace be upon him) visited me looking pleased and he said: 'A'isha, don't you see Mujazziz al-Mudliji? (He) entered (my house) and saw Usama and Zaid with a rug over them covering their heads, but their feet appeared, and (he) said: These feet are related to one another.