William Muir,
The Caliphate: Its Rise, Decline and Fall…
“ As the levies kept coming in, 'Omar sent them on, one after another, to join Sa'd. The numbers swelling rapidly, embraced the chivalry of all Arabia. Toleiha, the quondam prophet, now an exemplary believer, and 'Amr ibn Ma'dikerib, went in command of their respective tribes; and 'Omar wrote that each alone was worth a thousand men. ”
