Musannaf Ibn Abi Shaybah

Hazrat Hisham narrates from his father that among the companions of the Messenger of Allah, peace and blessings be upon him, there was a man who was called "Mas'ud." He was very much a talebearer. So, when it was the day of the Trench, Banu Qurayza sent a message to Abu Sufyan: "Send some men to us who will be stationed in our forts (as defenders), so that we may fight Muhammad from the (inner) side of Madinah, and you fight from the side of the trench." The Prophet, peace and blessings be upon him, found it difficult to fight on two fronts. The Prophet, peace and blessings be upon him, said to Mas'ud: "O Mas'ud! We have sent a message to Banu Qurayza that they should send their men to Abu Sufyan. When Abu Sufyan sends his men to them, the people of Banu Qurayza will kill them." When Mas'ud heard this, he could not restrain himself and went and told this to Abu Sufyan. Abu Sufyan said, "By God! Muhammad has always spoken the truth and has never lied." Thus, he did not send anyone to Banu Qurayza. (This action of the Prophet, peace and blessings be upon him, was part of a war strategy.)