Yazid bin Hurmuz says that Najdah wrote to Sayyiduna Ibn Abbas (may Allah be pleased with them both) asking him about certain things, and he mentioned his question and the answer of Sayyiduna Ibn Abbas (may Allah be pleased with them both). Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "You have asked about the woman and the slave, whether they have a share when they take part in the fighting. They have no fixed share, but they are to be given something as a gratuity from the spoils of the enemy."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12912