Tafsir of Al-Mursalat 77:41

Indeed, those who are righteous—meaning those who are righteous against disbelief and denial, due to this occurring in juxtaposition to the deniers of the Day of Recompense (and thus it includes the disobedient among the believers)—are in zilal (shades). Zilal is the plural of zill (shade), which is the opposite of dah (sunlight). It is more general than fay’ (afternoon shade); for one says "shades of night" and "shade of Paradise," and every place that the sun has not reached is called zill. Fay’, however, is only used for that from which the sun has moved away. It is also used to express luxury, honor, and invulnerability. Al-Raghib interpreted what is in the verse based on this latter meaning, while others interpreted it according to the well-known literal meaning. Both are supported by what preceded in the juxtaposition: "Proceed to a shadow having three columns," etc. Al-A‘mash read it as fi zullal, the plural of zullah (canopy). Regardless, the intended meaning of His saying, "Indeed, the righteous are in shades and springs," is...