Tafsir of At-Tawbah 9:50

{If a good thing befalls you} in some of your military expeditions {it grieves them}—that good thing, meaning it causes them distress and sorrow due to the excess of their envy (may Allah the Exalted curse them) and their hostility. {And if a disaster befalls you}—such as the defeat of an army or a hardship—{they say}, boasting of what they did and praising their own opinions, {“We had already taken our precautions”}, meaning: we had already rectified our affairs, intending by this their staying behind and refraining from war, their appeasement of the disbelievers, and other matters of disbelief and hypocrisy, both in word and deed. {“From before”}, meaning: before the disaster struck, at a time when taking precautions is of use. By this, they indicate that their conduct only finds favor with the disbelievers if it occurs while Islam is strong, not after a disaster has occurred. {And they turn away}—that is, they depart from those they are speaking to and from their place of gathering to their families and intimates, or they disperse, or they turn away from you, O Messenger of Allah—{while they are rejoicing} in what they have done and in the misfortune that has befallen you.

The sentence is in the position of a state (hal) for the pronoun in {they say} and {they turn away}, for the joy accompanies both actions together. The preference for the nominal sentence is to indicate the permanence of their joy. The second conditional was not constructed in the style of the first—by saying "And if a disaster befalls you, it pleases them"—but rather, something that implies that was put in its place as an exaggeration of their extreme joy, while signaling that they are oblivious to the evil of their conduct, as the context demands. It has been said: attributing the "grieving" to the "good thing" and the "pleasure" to themselves is to signal the difference in their state during the occurrence of both; in the former, they are compelled, and in the latter, they are choosing.

The "good thing" here is contrasted with "disaster," and is not contrasted with "evil" as He, the Exalted, said in Surah Ali ‘Imran: {And if an evil befalls you, they rejoice at it}, because the address here is to the Prophet (may Allah bless him and grant him peace), whereas there it is to the believers. There is a difference between the addressees, for hardship only increases the Prophet (may Allah bless him and grant him peace) in reward, as he is infallible in all his states (upon him be prayer and peace).

The restriction of the occurrence to "some" expeditions is due to the context indicating it. It does not refer to a specific "some"—namely, this expedition for which they sought permission to stay behind—which is evident. Yes, the occasion of revelation might imply that, for Ibn Abi Hatim recorded from Jabir ibn ‘Abdullah that he said: The hypocrites who remained in Medina began spreading bad news about the Prophet (may Allah bless him and grant him peace), saying: "Muhammad and his companions have struggled in their journey and have perished." Then the news of the falsity of their claims and the well-being of the Prophet (upon him be peace) and his companions reached them, so Allah the Exalted revealed the verse. Reflect on this.