Abu Wa'il narrates: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) heard a man saying: "Where are those who renounce this world and long for the Hereafter?" Sayyiduna Abdullah (may Allah be pleased with him) said: "Those people have gone; they were the people of al-Jabiyah. Five hundred Muslims made it a condition that they would not return until they were martyred. They shaved their heads, faced the enemy, and were all martyred, except the one man who brought the news about them."
Al-Tabarani recorded it. Its chain contains a narrator, Ali bin Asim, who makes many mistakes. The rest of its narrators are thiqat (trustworthy).