What is the ruling on insulting time or the day, and is expiation due from whoever insults them?

Cursing "ad-dahr" (time/fate) is Islamically forbidden, whether it is expressed as "ad-dahr," "az-zaman" (time), "al-yawm" (day), or "al-waqt" (time). This is based on the sacred Hadith (Hadith Qudsi): "The son of Adam harms Me; he curses ad-dahr, while I am ad-dahr; in My hand is the command; I alternate the night and the day." The reason for this prohibition is that Arabs used to attribute calamities to it, so cursing ad-dahr was, in reality, cursing Allah, the Almighty and Majestic, who is the true Doer.

Ibn al-Qayyim mentioned three grave corruptions associated with cursing ad-dahr: 1. Cursing that which is not deserving of curses, for ad-dahr is a creation subservient to Allah. 2. Cursing ad-dahr involves polytheism (shirk), as they mistakenly believe it can harm or benefit. 3. The curse falls upon the One who performs these actions, who is Allah the Almighty; thus, cursing ad-dahr is cursing Allah.

Ad-dahr is not among the names of Allah. Whoever falls into this sin must repent and seek forgiveness.