The Messenger of Allah ﷺ gave Urwah bin Abi J'ad Al-Bariqi (may Allah be pleased with him) a dinar to buy a sacrificial goat for him. Urwah (may Allah be pleased with him) says that I bought two goats for one dinar (then in the market itself) sold one goat for one dinar. I brought both the goat and the dinar to the Prophet ﷺ. So the Prophet ﷺ prayed for blessing in my buying and selling. After that, even if he bought dust, he would profit from it. (Meaning, whatever he bought, there was blessing in it.)
Hadith Referenceالسنن المأثورة / باب من أعتق شركا له في عبد / 559
Hadith Takhrijسنن ابی داؤد، البيوع، باب فی المضارب يخالف، رقم: 3384 وقال الالباني: صحيح، سنن ابن ماجه، الصدقات، باب الأميين يتجر فيه فيربح، رقم: 2402۔