عَن صُهَيْبٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ:" ثَلَاثٌ فِيهِنَّ الْبَرَكَةُ: الْبَيْعُ إِلَى أَجَلٍ والمقارضة واخلاط الْبُرِّ بِالشَّعِيرِ لِلْبَيْتِ لَا لِلْبَيْعِ ". رَوَاهُ ابْنُ مَاجَه

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.