Quran 31.16-17
O my dear son! Lo! though it be but the weight of a grain of mustard-seed, and though it be in a rock, or in the heavens, or in the earth, Allah will bring it forth. Lo! Allah is Subtile, Aware. O my dear son! Establish worship and enjoin kindness and forbid iniquity, and persevere whatever may befall thee. Lo! that is of the steadfast heart of things.