Tafsir of Al-Mutaffifeen 83:31

"And when they returned" — meaning the criminals — "to their people," they returned "gleeful," finding pleasure in their mockery of the believers. The intent behind this is to indicate that they considered this action of theirs among the best of what they had acquired during their absence from their families; or that it held a [significant] impact on their hearts, and they did not do it out of consideration for anyone, but rather for the sake of their own selves. It has also been said that it contains an indication that they would not do this when seeing those who passed by them, at which point they would suffice themselves with exchanging winks.

The majority read "fākihīn" with an alif [meaning those who enjoy humor and merriment]. It has been said that both ["fākihīn" and "fakkihīn"] have the same meaning. It has also been said: "fariḥīn" [joyful]. Regarding "fākihīn," it has been said: those who are amused and living in luxury; and it has been said: those who are engaging in banter.