Sayaqoolu almukhallafoona itha intalaqtum ila maghanima lita'khuthooha tharoona nattabiAAkum yureedoona an yubaddiloo (surah Al Fath: 15)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(48:15) When you press forth for the spoils, those who were left behind will say: 'Let us accompany you.' *27 They want to change the command of Allah. *28 Say to them (in clear words): 'You shall not accompany us. Thus has Allah already said.' *29 Then they will say: 'Nay; but you are jealous of us.' The truth is that they understand little.

Sa yaqoolul mukhalla foona izan talaqtum ilaa maghaanima litaakhuzoohaa zaroonaa nattabi`kum yureedoona any yubaddiloo Kalaamallaah; qul lan tattabi`oonaa kazaalikum qaalal laahu min qablu fasa yaqooloona bal tahsudoonanna; bal kaanoo laa yafqahoona illaa qaleela

*27) That is, `The time is approaching when these very people who were shirking accompanying you on the dangerous journey, would see you going on an expedition in which there would be the possibility of attaining easy victory and much booty. Then they would come running and request you to take them also along." Such a time came just three months after the truce of Hudaibiyah, when the Holy Prophet invaded Khaiber and took it easily. At that time everyone could see that after the truce with the Quraish not only Khaiber but the Jewish settlements of Taima, Fadak, Wadi-al-Qura' and others also of northern Arabia would not be able to withstand the might of the Muslims and would easily fall to the Islamic State. Therefore, Allah in these verses forewarned the Holy Prophet that the opportunists of the suburbs of Madinah would come up to take part in and receive their share when they would see easy victories being attained, and that he should tell them plainly: "You will never be allowed to take part in these, because only those who had gone forth to offer their lives in the conflict at Hudaibiyah regardless of every danger would be entitled o them. "
*28) "Allah's decree" implies the decree that only those people would be allowed to accompany the Holy Prophet in the expedition to Khaiber, who had taken part in the expedition to Hudaibiyah and sworn the pledge there for AIIah has reserved the spoils of Khaiber cxclusively for them; as has been stated clearly in verse 18 blow.
*29) The words "Allah has already said this before" caused the people the misunderstanding that this refers to some other command bearing upon the same subject that might have been sent down before this verse, and since no such command is found in this Surah before this verse, they started looking for it at other places in the Qur'an till they found verse 84 of Surah At-Taubah, in which this very subject has been dealt with for another occasion. But that verse, in fact, does not apply to this, for it was sent down in connection with the Battle of Tabuk, and its period of revelation is three years after the period of revelation of Surah AI-Fat-h. The fact of the matter is that this verse refers to vv. 18-19 of this Surah itself, and Allah's already having said this does not mean its having been said before this verse but its having boon said to the laggards before this conversation. This conversation with the laggards about which advance instructions are being given to the Holy Prophet was to take place at the time of the expedition to Khaiber, and this whole Surah, including vv. 18-19, had been sent down three months earlier on return from Hudaibiyah on the way. A careful study of the context shows that Allah here is giving this instruction to His Messenger: "When after your return at Madinah the laggards come to you with their excuses, you should give them this reply, and when they express their desire to accompany you in the expedition to Khaiber, you should tell them this. "