Overall meaning :
Almighty Allah instructs His believing servants to take all necessary precautions against their enemies and to go forth into battle against them in parties—one detachment after another—or all together.
Then He warns the faithful, stating that there are hypocrites in their midst who are too sluggish to go forth to fight in Allah’s cause and who lag behind and discourage others from going into battle. If a misfortune befalls the believers going forth to war, these hypocrites say, ‘Allah has been gracious to us that we did not go to war with them, otherwise we would have suffered the same fate.’ But if the believers triumph over their enemy and carry off their spoils, they say, as if there had never been any affection between them and the believers, ‘If only we had gone forth into battle along with them so that we would have had a share in the spoils they have seized from their enemy.’
After that, Allah exhorts the true believers, who genuinely seek His favour and reward and are willing to barter the life of this world for the life to come, to fight in His cause, promising a rich reward to whoever fights in His cause, whether he is killed or emerges victorious.
Then He urges the faithful to fight in His cause, saying: What prevents you from fighting in the cause of Allah to uphold His religion and make it supreme and to rescue the oppressed and helpless men, women and children who beseech their Lord to take them out of Makkah whose people among the idolaters have oppressed them and to send them, out of His grace, a protector and supporter to help them against their enemy?
After that, He declares that the true believers fight to uphold His religion, while the unbelievers fight in the cause of Satan, and commands the believers to fight those who support and obey Satan, stating that Satan’s scheming is rather feeble.