Fussilat: (40) "Indeed, those who deviate..."
"It is said: 'Alhada' (أَلْحَدَ) and 'Lahada' (لَحَدَ) the digger, when he deviates from the straight path, digging into the side [of the grave]."
It is metaphorically applied to deviating in the interpretation of the verses of the Qur'an away from the direction of correctness and rectitude. It is recited as both yulhidūna (يُلْحِدُونَ) and yalhadūna (يَلْحَدُونَ), according to the two linguistic dialects. His saying, "They are not hidden from Us," is a threat to them for their distortion.
(41) "Indeed, those who disbelieve in the Reminder when it comes to them. And indeed, it is a Mighty Book. (42) Falsehood cannot approach it from before it or from behind it; [it is] a revelation from a Wise, Praiseworthy [One]."