Muhammed bin Abi Haatim (rahimahullah) reports that when Imaam Bukhaari’s (rahimahullah) father passed away, Imaam Bukhaari (rahimahullah) inherited a large amount of wealth from him. Imaam Bukhaari (rahimahullah) would invest this wealth in mudhaarabah partnerships (a partnership where one partner puts up the capital and the other does the work of engaging in trade), and it was through this that he would earn an income. (Hadyus Saari pg. 479)

Imaam Bukhaari (rahimahullah) would spend the money that he earned upon himself and use the money in the pursuit of acquiring the knowledge of Hadith. He would also spend generously on the students of deen and would give abundantly in charity.