After discovering 150,000 shekels hidden in a wall during renovations, a Slabodka Kollel student in Bnei Brak sought halachic guidance. He then returned the money to the unaware, but extremely grateful, non-religious seller from whom he had bought the apartment. B”H.

https://worldisraelnews.com/ultra-orthodox-student-returns-150000-nis-he-discovered-after-buying-apartment/