The Invasion of Sawiq was a small reconnaissance by the Quraysh. After suffering the ignominious defeat at the Battle of Badr, Abu Sufyan ibn Harb, the Quraysh leader gathered two hundred mounted men, took the eastern road through the Nejd and secretly arrived by night, at the settlement of Banu Nadir, a Jewish tribe. However, the Jewish chief, Huwey refused him admission to the Jewish quarters (reportedly out of fear). So, Abu Sufyan took refuge with Salam bin Mishkan, another leader of the Banu Nadir tribe of Jews. Salam gave Abu Sufyan’s a hospitable welcome, and the intelligence regarding Medina. At night, Abu Sufyan took him men to the corn fields Urayd, a place about two or three miles to the north-east of Medina. He burnt these farms and killed 2 Muslims. When Muhammad found out, he gathered his men in hot pursuit. They could not catch up to them. The Muslims collected some of the provisions thrown away by the Quraysh men and brought back some Sawiq (a type of flour).
This event is mentioned in Ibn Hisham's biography of Muhammad, and other historical books. Modern secondary sources which mention this, include the award winning book,Ar-Raheeq Al-Makhtum (The Sealed Nectar)