Tafsir of Fatir 35:21

"Nor the shadow and nor the heat" (35:21). That is, nor the reward and nor the punishment. It is also said: nor Paradise and nor the Fire.

"Al-Harur" (the heat) is a noun on the measure of fa'ul derived from al-harr (heat). It is applied, as reported from al-Farra', to intense heat, whether by night or by day. Abu al-Baqa' said: It is the intense heat of the sun. In al-Kashshaf, it is stated that al-harur is the scorching wind (al-samum), except that al-samum occurs during the day, whereas al-harur occurs by night and day. It is also said: only by night.