Abu Dawud
Commercial Transactions
Book Number: 016 / Hadith Number: 3378
Narated By Urwah ibn AbulJa'd al-Bariqi : The Prophet (pbuh) gave him a dinar to buy a sacrificial animal or a sheep. He bought two sheep, sold one of them for a dinar, and brought him a sheep and dinar. So he invoked a blessing on him in his business dealing, and he was such that if had he bought dust he would have made a profit from it.