Hmam bin Yahya bin Dinar همام بن يحيى بن دينار · The Book of Zakah

"While we were with the Messenger of Allah in the early hours of the morning, some people came who were naked and barefoot, with their swords hung (around their necks). Most of them, may all of them, belonged to the tribe of Mudar. The face of the Messenger of Allah changed when he saw them in poverty. He went in (to his house) then he came out and ordered Bilah to call the Adhan and then the Iqamah. He (the…