Maliks Muwatta Book 37, Hadith Number 6B.
Yahya said that he heard Malik speak about a man who bought goods – animals or clothes or wares, and the sale was found not to be permitted so it was revoked and the one who had taken the goods was ordered to return the owner his goods. Malik said, “The owner of the goods only has their value on the day they were taken from him, and not on the day they are returned to him. That is because the man is liable for them from the day he took them and whatever loss is in them after that is against him. For that reason, their increase and growth are also his. A man may take the goods at a time when they are selling well and are in demand, and then have to return them at a time when they have fallen in price and no one wants them. For instance, the man may take the goods from the other man, and sell them for ten dinars or keep them while their price is that. Then he may have to return them while their price is only a dinar. He should not go off with nine dinars from the man’s property. Or perhaps they are taken by the man, and he sells them for a dinar or keeps them, while their price is only a dinar, then he has to return them, and their value on the day he returns them is ten dinars. The one who took them does not have to pay nine dinars from his property to the owner. He is only obliged to pay the value of what he took possession of on the day it was taken.”
He said, “Part of what clarifies this is that when a thief steals goods, only their price on the day he stole them is looked at. If cutting off the hand is necessary because of it, that is done. If the cutting off is delayed, either because the thief is imprisoned until his situation is examined or he flees and then is caught, the delay of the cutting off of the hand does not make the hadd, which was obliged for him on the day he stole, fall from him even if those goods become cheap after that. Nor does delay oblige cutting off the hand if it was not obliged on the day he took those goods, even if they become expensive after that.”