Is taking spoils of war from those attacked while unaware permissible?
General Chapter
Al-Mughni
Book of Jihad
Primary text
It is permissible to attack settlements of polytheists while they are unaware, and to take the spoils and captives among their non-combatant population, based on the Hadith narrated by Ibn Umar where the Prophet (peace be upon him) raided Bani al-Mustaliq while they were unaware, killing the fighters and taking the women and children captive. Similarly, the Prophet's statement that if raiding parties strike the women and children of enemy settlements without prior knowledge, they are considered part of the enemy group, supports this.
Supporting text
There is an interpretation suggesting that the command to invite before battle, as established in Buraydah’s Hadith, may be one of recommendation (Istihbab) in all situations. This is supported by the instance where the Prophet commanded Ali to invite the people of Khaybar, even though the message had reached them.