Sayyiduna Buraydah (may Allah be pleased with him) narrates: On the occasion of the Battle of Hunayn, the people scattered, leaving the Prophet (peace and blessings be upon him). Only one man remained with him, whose name was Zayd; he was holding the reins of the Prophet's mule, al-Shahba'. The Prophet (peace and blessings be upon him) said to him: "Woe to you! Call the people." Zayd called out loudly: "O people! This is the Messenger of Allah calling you." But no one came. The Prophet (peace and blessings be upon him) said: "Call the Ansar." He said: "O company of the Ansar! The Messenger of Allah is calling you." But no one came. The Prophet (peace and blessings be upon him) said: "Woe to you! Call the Aws and the Khazraj specifically." So he called out: "O company of the Aws and the Khazraj! This is the Messenger of Allah calling you." But no one came. The Prophet (peace and blessings be upon him) said: "Call the Muhajirun specifically, for my pledge of allegiance is upon their necks." The narrator says: Sayyiduna Buraydah (may Allah be pleased with him) told me that then a thousand of them came, having cast aside their scabbards. They came to the Prophet (peace and blessings be upon him), and then they began to advance, until Allah Almighty granted them victory.
Al-Bazzar recorded it, and its narrators are thiqat (trustworthy).