Tafsir of At-Tawbah 9:81

{The Mukhallafun (those who stayed behind) rejoiced in their sitting...}

{The Mukhallafun}: Those among the hypocrites who sought permission from the Messenger of Allah (ﷺ) to stay behind, and he granted it to them, leaving them in Medina during the expedition of Tabuk. Or, they are those whom their laziness, hypocrisy, and Satan left behind.

{In their sitting}: In their remaining behind from the expedition.

{Contrary to the Messenger of Allah}: Behind him. It is said: "He stayed khilafa (contrary to/behind) the tribe," meaning they departed and he did not depart with them. This is supported by the reading of Abu Haywah: khalfa (behind) the Messenger of Allah. It is also said that it means "opposition," because they opposed him by sitting while he rose to depart. Its grammatical position is that of a maf‘ul lahu (causative object) or a hal (state), meaning: they sat to oppose him, or while opposing him.

{That they should not strive with their wealth and their lives}: This is a taunt against the believers, regarding their endurance of immense hardships for the sake of Allah, their sacrifice of their wealth and souls in the path of Allah, and their preference for this over ease and comfort. The hypocrites hated this. And how could they not hate it, when they lack the motive of faith and the call of certainty that the believers possess?

{Say: "The fire of Hell is more intense in heat"}: This is to declare them ignorant. For whoever protects himself from the hardship of an hour, and because of that protection falls into the hardship of eternity, is more ignorant than any ignorant person. As one poet said:

A joy of ages, followed by A day of misery, I see as bitter as colocynth. So how is it to meet the joy of an hour, Followed by the misery of ages?

{So let them laugh a little and weep much, as a recompense for what they used to earn.}