Tafsir of Al-Waqi'ah 56:65

"If We willed, We could make it hutaman"—that is, hashiman (broken into pieces) due to its extreme dryness after We have caused it to grow and it had reached the point where you were expecting to harvest its crops.

"Then you would remain tafakkahun"—meaning, you would marvel at its wretched state after having witnessed it in the best possible condition, according to what has been narrated from Ibn Abbas, Mujahid, and Qatadah. Al-Hasan said: "You would regret," meaning [regretting] what you pursued in it and what you spent upon it without achieving any benefit, or for the sins you committed for its sake. Ikrimah said: "You would blame one another for what you have done."

Tafakkuh refers to consuming various types of fruits, and it is metaphorically used for "consuming" conversation; here, it refers to what is said after the destruction of the crops. It is used as a metonym in the verse for marveling, regretting, or blaming one another, according to the varying interpretations. In Al-Bahr, it is stated that all of these are interpretations based on the consequential meaning. The meaning of tafakkahun is "you cast off fukahah (joy) from yourselves," for fukahah is happiness; a man is fakih (jovial/lighthearted) when his soul is at ease and he is not bothered by anything. The verb tafakkaha is one of the verbs of removal (like taharraja and tahawwaba), meaning the tafa‘‘ul form here signifies the removal of the quality.

Abu Haywah and Abu Bakr, in a narration from Al-Ataki, read it as faziltum with a kasra on the za’, just as they say mista (with kasra) and masta (with fatha). Al-Thawri reported this from Ibn Mas’ud, and it has also come from Al-A’mash. Abdullah and Al-Jahdari read it as fazallaltum with two lams, the first of which is maksurah (with a kasra). Al-Jahdari also read it with a fatha on the lam. The well-known reading is zaliltum with a kasra. Abu Hizam read it as tafakkununa with an nun in place of the ha’. Ibn Khalawayh said: tafakkaha with a ha’ means to marvel, and tafakkuna with an nun means to regret.