The benefits of the saying of Allah the Exalted: << وربك يعلم ما تكن صدورهم وما يعلنون >

In this is the affirmation of knowledge for Allah, and that it encompasses what is concealed and what is declared.
Among its benefits are warning and encouragement. How are they a warning and an encouragement? It warns a person against concealing or declaring evil, because Allah knows it, and encourages him to conceal or declare good, because Allah knows it. And Allah knows best what is concealed of good or evil, meaning that it will not be lost; it is known, as Allah, Blessed and Exalted is He, said in many verses that He knows and will inform on the Day of Resurrection about what these people did. So in the verse there is encouragement and warning: whoever conceals good and declares it, that is encouragement for him, and whoever conceals evil or declares it, that is a warning for him.