Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: A man was given the command to keep himself steadfast, (such that) ten (would stand firm) against a hundred, because the Muslims were few. Then when the number of Muslims increased, Allah, the Mighty and Majestic, commanded that one man stand firm against two, ten against twenty, and a hundred against two hundred.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11600