It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) borrowed coats of mail and weapons from Safwan bin Umayyah during the Battle of Hunayn. He said: O Messenger of Allah! Is a borrowed item to be returned? He (peace and blessings be upon him) said the same: "A borrowed item is to be returned."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العارية / 11475