Malik ibn Aws ibn al-Hadathan said, "The Prophet, may Allah bless
him and grant him peace, went out to open ground to answer a call of nature
and did not find anyone to follow him. 'Umar went out and followed him
with a clay pot or wudu' vessel. He found him prostrating in a river bed.
He fell back and sat behind him until the Prophet, may Allah bless him
and grant him peace, lifted his head. He said, 'You have done well, 'Umar.
When you found me prostrating, you went behind me. Jibril came to me and
said, 'If someone says the prayer on you once, Allah will pray ten times
on him and raise him ten degrees.'"