حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ الْعَبْدِيُّ، أَخْبَرَنَا سُفْيَانُ، حَدَّثَنِي أَبُو حُصَيْنٍ، عَنْ شَيْخٍ، مِنْ أَهْلِ الْمَدِينَةِ عَنْ حَكِيمِ بْنِ حِزَامٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم بَعَثَ مَعَهُ بِدِينَارٍ يَشْتَرِي لَهُ أُضْحِيَةً فَاشْتَرَاهَا بِدِينَارٍ وَبَاعَهَا بِدِينَارَيْنِ فَرَجَعَ فَاشْتَرَى لَهُ أُضْحِيَةً بِدِينَارٍ وَجَاءَ بِدِينَارٍ إِلَى النَّبِيِّ صلى الله عليه وسلم فَتَصَدَّقَ بِهِ النَّبِيُّ صلى الله عليه وسلم وَدَعَا لَهُ أَنْ يُبَارَكَ لَهُ فِي تِجَارَتِهِ ‏.‏

Narrated Hakim ibn Hizam: The Messenger of Allah (PBUH) sent with him a dinar to buy a sacrificial animal for him. He bought a sheep for a dinar, sold it for two and then returned and bought a sacrificial animal for a dinar for him and brought the (extra) dinar to the Prophet (PBUH). The Prophet (PBUH) gave it as alms (sadaqah) and invoked blessing on him in his trading. Translation Not Available

Book Ref: Sunan Abi Dawud Book 23 Hadith 3386
Web Ref:  Sunan Abi Dawud Book 22 Hadith 3380