Musannaf Ibn Abi Shayba 28:711

'Abd al-Rahim ibn Sulayman narrated to us, from Yahya ibn Sa'id, who said: I mentioned to Sa'id ibn al-Musayyib, saying: "I went on a military expedition to the frontier (al-darb). When we turned back, they sent out raiding parties (sariyya) after we had already turned back. It was said to you: 'You have no share of the spoils except for the fifth.'" Sa'id ibn al-Musayyib said: "People were not given extra shares (nafal) except from the fifth."