Sayyiduna Abu Musa (may Allah be pleased with him) says: When the Messenger of Allah (peace and blessings be upon him) had finished with the battle of Hunayn, he sent Abu Amir (may Allah be pleased with him) as commander of a detachment towards Awtas, against Durayd bin al-Simmah. He met him, and he (Durayd) was killed, and Allah Almighty defeated his companions.
Imam al-Shafi'i (may Allah have mercy on him) says: Abu Amir (may Allah be pleased with him) was in the army of the Prophet (peace and blessings be upon him) at the battle of Hunayn. The Prophet (peace and blessings be upon him) sent him in pursuit of them. This was one army, each part of it a support for the other. When an army is of this kind, whoever gains spoils, the army and the separate detachment are both partners in it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17957
Amr bin Shu'ayb narrates from his father, from his grandfather (Sayyiduna Abdullah bin Amr (may Allah be pleased with them both)), that in the year of the Conquest the Messenger of Allah (peace and blessings be upon him) delivered a sermon in which he said: "The Muslims are one hand against those besides them; the lowest of them may grant protection on their behalf; the farthest of them returns (a share) to them; and their raiding detachments return (a share of the spoils) to those of them who stayed behind." In the narration of Yahya bin Sa'id from Amr: "The one with the strong mount among them returns (a share) to the one with the weak mount, and the one who hastens ahead returns (a share) to the one who stays behind."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17958