Quraysh had broken the treaty of al-Hudaybiyah by arming an ally against Khuzaʿah, who were in the Prophet’s ﷺ protection. He moved on Mecca with ten thousand men and kept the destination secret to the last.
The army camped a night’s march out at Marr al-Zahran and every man was ordered to light his own fire. Ten thousand fires came up out of the valley at once — a message, not an accident.
Abu Sufyan came out to see what it was, was brought in under al-ʿAbbas’s ﵁ protection, and accepted Islam before morning. He was sent back with the terms: whoever entered his house, or the Sacred Mosque, or shut his own door, was safe.