Amr bin Harish said: I said to Abdullah bin Amr bin al-As (may Allah be pleased with them both): We live in a land where there is no gold or silver; may we buy one cow for two, one camel for two camels, and one goat for two goats? Abdullah bin Amr bin al-As (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) ordered me to equip an army, and the camels ran out. I said: O Messenger of Allah (peace and blessings be upon him)! The camels have run out. He (peace and blessings be upon him) said: "Take the sadaqah camels." He said: So I would take one camel for two, (payable) from the sadaqah camels.
The narrators differed over Muhammad bin Ishaq in its chain; Hammad bin Salamah's version is the best of them in wording, and it has an authentic supporting report (shahid).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10528