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