Overall meaning : The Almighty says: To Allah alone submit all those who are in the heavens and the earth: the believers do so willingly and the unbelievers unwillingly (because they disdain to worship Him but their condition and natural inclination to surrender to Allah prove them wrong), and so do their shadows in the morning and the evening.
Say, Muhammad, to the idolaters among your people who associate partners with Allah, ‘Who is the Creator of the heavens and the earth and who regulates all their affairs?’ Say, ‘It is Allah.’ Say to them, asking them to produce evidence for their false worship, ‘Why, then, have you taken besides Him false deities that can neither benefit nor harm even themselves, let alone benefit or harm you?’ Say to them, ‘Are the unbelievers who are blind to the truth equal to the believers who see it? Is unbelief which is all darkness equal to faith which is all light?’ Or have they ascribed to Allah partners who have created something similar to what He has created, so that their creation appears to them like His? Say, ‘Allah alone—and not the idols that do neither harm nor good—is the Creator of all things, and He is the One, who alone is worthy of worship; the Supreme and Irresistible, who holds absolute sway over all creation.’
Allah then gives two examples of truth and falsehood: He sends down water from the sky, causing valleys to flow, each according to its capacity, and the torrent carries along the way a swelling worthless scum on its surface. A similar kind of scum comes from the metals, such as gold and silver, which you smelt in the fire in order to make ornaments, or copper which you smelt to use for other benefits. Thus does Allah illustrate truth and falsehood. Falsehood, just like the scum on the surface of water or that attached to metals when they are smelted in the fire, is rather worthless and so it simply vanishes or is cast away. As for the truth, which is like pure water and pure metals, it remains behind on the earth so people may benefit form it. Just as Allah sets forth these parables to show you that the truth remains and falsehood vanishes, so, too, He strikes parables to people to distinguish truth from falsehood and guidance from misguidance.
Next, Allah, Exalted be He, mentions the ultimate outcome of those who follow the truth and that of those who follow falsehood: The believers who obey Allah and His Messenger will have the finest reward—Paradise. As for those who do not believe in Him and do not obey Him and His Messenger, even if they were to possess everything in the world twice over, they would certainly offer it to ransom themselves from Allah’s punishment of the Day of Judgement but it will still not be accepted from them; they will face strict judgement and be called to a terrible account for all their evil deeds, and their permanent home will be Hell. What a bed of misery and an evil resting-place they have prepared for themselves!