Tafsir of Al-Furqan 25:73

"And those who, when they are reminded of the verses of their Lord"—which are the Quranic [verses] that encompass exhortations and rulings—"do not fall upon them deaf and blind"—meaning they do not cast themselves upon them as ones who hear with attentive ears and see with watchful eyes. The negation here is directed toward the restriction [of being deaf and blind], which is the most frequent usage in the language of the Arabs. The expression [used here] instead of saying "they fell upon them hearing and seeing" serves as an insinuation regarding the state of the disbelievers and hypocrites when they are reminded of the verses of their Lord.

Al-khurur (falling) is falling without order or sequence. Using this term carries an exaggeration regarding the impact that the reminder has upon them.

It has been said: The pronoun in "upon them" refers to the sins implied by "vain talk" (al-laghw). The meaning is: when they are reminded of the verses of their Lord that contain the prohibition of sins and the warning to those who commit them, they do not commit them, and they are not like those who do not hear and do not see. And this [interpretation], as you can see, is [far-fetched].