Tafsir of An-Naml 27:85

"And the decree will befall them" means the punishment will descend upon them, which is what is signified by the decree that pronounces its arrival, "for they have done wrong," meaning because of their wrongdoing, which is their denial of the signs of Allah Almighty. "So they will not speak," in defense, because it will be entirely negated for them, and because they will be stunned by the painful punishment that has befallen them.

It is also said: Their mouths will be sealed, so they will not be able to utter anything at all. In al-Bahr, it is mentioned that the negation of their speech applies to one of the stations of the Day of Resurrection, or to a specific group of people, for the Noble Quran explicitly states that they will speak in certain situations, offering excuses and seeking salvation from the Fire.