Ad-Dukhan: (58) "So We have only made it easy by your tongue..."

"So We have only made it easy" means: We have facilitated the Quran.

"By your tongue" means: By your language. It is also said that the meaning is: We revealed it upon your tongue without it being written down, because you are unlettered.

This is a summary and a consolidation of what is in the Surah after having detailed it, as a reminder of what has previously been explained therein. Thus, the meaning is: Remind them with the Clear Book, "for We have only made it easy by your tongue."

"That they might take heed" means: So that they may understand it, be reminded by it, and act in accordance with its requirements.

"So watch" means: Even if they do not take heed, then wait for what will befall them. This is a generalization following the specification mentioned in His saying, the Exalted: [referring to the subsequent threat].