Mishkat al-Masabih 11 Business Transactions كتاب البيوع 173

وَعَن حَكِيم بن حزَام أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بَعَثَ مَعَهُ بِدِينَارٍ لِيَشْتَرِيَ لَهُ بِهِ أُضْحِيَّةً فَاشْتَرَى كَبْشًا بِدِينَارٍ وَبَاعَهُ بِدِينَارَيْنِ فَرَجَعَ فَاشْتَرَى أُضْحِيَّةً بِدِينَارٍ فَجَاءَ بِهَا وَبِالدِّينَارِ الَّذِي اسْتَفْضَلَ من الْأُخْرَى فَتصدق رَسُول الله صلى بِالدِّينَارِ فَدَعَا لَهُ أَنْ يُبَارَكَ لَهُ فِي تِجَارَته. رَوَاهُ التِّرْمِذِيّ

Hakim b. Hizam said God’s Messenger sent him with a dinar to buy a sacrificial animal for him. He bought a sheep for a dinar, sold it for two, came back, bought a sacrificial animal for a dinar, and brought it along with the extra dinar which he had gained. God’s Messenger gave the dinar as sadaqa and asked a blessing on him in his trading. Tirmidhi and Abu Dawud transmitted it.