Blessing over Hidden Things in Halacha

Shalom and blessings. 

The source is Torat Chaim, Baba Metzia 47a: The phrase 'that which is hidden from the eye' should not be understood solely as referring to the evil eye. In the context where a learned person goes to thresh his grain, it also states this. It is clear that a person does not cause the evil eye to afflict themselves. Rather, the reason is that honor, miracles, and blessings come only in secret, as is known from the story of Elisha, who said: 'And you come and shut the door behind you,' etc. Therefore, there is a concept that blessings rest upon things that are concealed from public view.