Tafsir of Al-Muddathir 74:45

This means we would enter into falsehood along with those who were engaging in it. The word al-khawd (indulgence) originally refers to entering into water and passing through it. Its usage regarding engaging in falsehood is either from the metaphorical category of al-majaz al-mursal (synecdoche) or from metaphor (isti'arah), as established in al-Mutawwal and similar works.

Some have stated that it is a name predominantly used for evil, and it is mostly used in the Quran in contexts where engaging in something is blameworthy. By "falsehood" (al-batil), it is meant everything that is inappropriate in terms of speech and action. This includes: relating what takes place between spouses in private; recounting the conditions of the immoral in their various forms for the sake of enjoyment and entertainment; narrating the wars that occurred between the Companions—may Allah be pleased with them—not for any legal purpose, but merely to use it as a means to slander and belittle; and speaking a word to make one’s companions laugh, regardless of whether the word is permissible in itself or not. Indeed, speaking a forbidden word for that purpose is falsehood upon falsehood, in addition to countless other examples.

The mention of "with those who indulge" is an indication of their lack of concern for falsehood and their indifference toward it. It is as if they were saying: "We did not care about the falsehood."