Tafsir of Ar-Rum 30:41

{Corruption has appeared on land and sea} This refers to drought, famine, a decrease in agricultural yields and commercial profits, the occurrence of epidemics among people and livestock, the frequency of fires and drownings, the failure of hunters and divers, the removal of blessings from all things, and, in general, a scarcity of benefits and an abundance of harms.

Ibn Abbas said: "The earth became barren, and the resources of the sea were cut off." It is said that when rain ceases, the creatures of the sea become blind. Al-Hasan said that "the sea" refers to the coastal cities and villages. Ikrimah said: "The Arabs call the great cities 'seas'." It is also recited as: fi al-barri wa al-buhur (on land and in the seas).

{Because of what the hands of the people have earned} This is due to their acts of disobedience and sins, similar to the Almighty’s saying: “And whatever strikes you of disaster, it is for what your hands have earned” (Ash-Shura: 30).

Ibn Abbas said: "Corruption appeared on land" through the son of Adam killing his brother. "And in the sea," because Julundi (a tyrant king) used to seize every ship by force. Qatadah said: "This was before the mission of the Prophet; when the Messenger of Allah (ﷺ) was sent, many returned from misguidance and oppression." It is also possible that it means the appearance of evil and sins through the people's own actions.

If you ask: What is the meaning of His saying: {That He may let them taste part of what they have done, so that perhaps they may return?}

I say: According to the first interpretation, it is clear: Allah has corrupted the causes of their worldly life and diminished them so that they may taste the consequence of some of their deeds in this world before He punishes them for all of them in the Hereafter, so that they might return from their state.

As for the second interpretation, the lam (in li-yudhiqahum) is metaphorical; it means that the appearance of evils caused by them is what made them deserving of Allah letting them taste the consequence of their deeds, with the intent of their return. It is as if they only caused corruption and were the reason for the spread of sins on earth for that very purpose. It is also recited as li-nudhiqahum (that We may let them taste) with the letter nun.

{Say, "Travel through the land and observe how was the end of those before. Most of them were polytheists."}