Imam al-Shafi'i (may Allah have mercy on him) said: The Prophet (peace and blessings be upon him) fought battles, and some people whose hypocrisy was evident also fought alongside him (peace and blessings be upon him), and on the day of Uhud three hundred men broke away from him. The Shaykh said: This is explained in the Maghazi.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17859