He sends down from the sky, rain, and valleys flow according to their capacity, and the torrent carries a rising foam. And from that [ore] which they heat in the fire, desiring adornments and utensils, is a foam like it. Thus Allāh presents [the example of] truth and falsehood. As for the foam, it vanishes, [being] cast off; but as for that which benefits the people, it remains on the earth. Thus does Allāh present examples.

Surah Ar-Ra’d, 17

Allah SWT presents parables in the above ayah for us to reflect and understand.

Rain is likened to wahiy. Rain gives life to the earth, similar to how knowledge from Revelation gives life to the heart.

As rain descends, just like a valley takes water according to its capacity, each person’s heart takes knowledge according to his/her capacity. The hearts differ, as some retain much knowledge while others forget. Bigger hearts will take in substantial knowledge similar to how a deeper valley will have more water.

As rain falls, the torrent causes foam to rise to its surface. The foam is impurities pushed aside leaving the purest form of water. As knowledge begins to flow in a person’s heart, doubts rise up and are cast aside, like the foam of the water. Continuous intake of knowledge will remove one’s doubts, jealousies, hypocrisies, leaving a purer heart.

A similar foam appears when the earth’s minerals are heated like gold, silver, and iron. Its impurities and scum rise to its surface and vanish. What remains is the purified form of metal used to benefit people by making jewelry and goods.

Through these parables, Allah presents the example of truthhood and falsehood. The foam and scum of the water and metal are cast off. They are worthless. This is falsehood which is cast off and useless. The purer form of water and metals remain from which people derive much benefit. What remains and lasts on the earth is what benefits people. This is like the truth that prevails.