Abu Karayb, Muhammad bin al-'Ala' محمد بن العلاء - أبو كريب · Commercial Transactions (Kitab Al-Buyu)

The Prophet (ﷺ) said: A time is certainly coming to mankind when only the receiver of usury will remain, and if he does not receive it, some of its vapour will reach him. Ibn Isa said: Some of its dust will reach him.

The Messenger of Allah (ﷺ) 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 (ﷺ). The Prophet (ﷺ) gave it as alms (sadaqah) and invoked blessing on him in his trading.