Sa'id bin al-Musayyib (may Allah have mercy on him) said that the Messenger of Allah (peace and blessings be upon him) said: "The benefit of a pledged item is not to be withheld from the one who pledged it. Its gain is his and its loss is his."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرهن / 11210