فَإِن رَّجَعَكَ ٱللَّهُ إِلَىٰ طَآئِفَةٍ مِّنْهُمْ فَٱسْتَـْٔذَنُوكَ لِلْخُرُوجِ فَقُل لَّن تَخْرُجُوا۟ مَعِىَ أَبَدًا وَلَن تُقَٰتِلُوا۟ مَعِىَ عَدُوًّا ۖ إِنَّكُمْ رَضِيتُم بِٱلْقُعُودِ أَوَّلَ مَرَّةٍ فَٱقْعُدُوا۟ مَعَ ٱلْخَٰلِفِينَ
Commentary:
The verse was probably revealed when the Holy Prophet was away from Medina during his expedition to Tabuk. But if, as some commentators think, it was revealed after his return to Medina, it would be taken to allude to what the hypocrites previously used to say regarding the said expedition. They thought that he would never return from the expedition alive. So the Quran, in this verse reminds them of what they used to say about the Holy Prophet, and of his safe return, contrary to their expectation.
The particle ان (if), it should be noted, does not always express doubt but is often used as simply a conditional particle. Moreover, it is sometimes used not from the point of view of the speaker, but from that of the person addressed. The word is here used by God and it is obvious that God had no doubt as to the safe return of the Prophet. So it must be taken to express the state of mind of the hypocrites.