Ibn Awn (may Allah have mercy on him) narrates: I wrote to Nafi' (may Allah have mercy on him) asking whether the call to Islam used to be given before fighting. He wrote back to me that this was at the beginning of Islam, and that the Messenger of Allah (peace and blessings be upon him) made a surprise attack on Banu al-Mustaliq while they were unaware and their livestock were being watered. He (peace and blessings be upon him) killed their fighting men and took their captives, and among them was Sayyidah Juwayriyah bint al-Harith (may Allah be pleased with her). This hadith was narrated to me by Abdullah bin Muhammad, who was in that very army on that day.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20527