Word by Word Analysis

فَإِنْ خِفْتُمْ فَرِجَالًا أَوْ رُكْبَانًا ۖ فَإِذَآ أَمِنتُمْ فَٱذْكُرُوا۟ ٱللَّهَ كَمَا عَلَّمَكُم مَّا لَمْ تَكُونُوا۟ تَعْلَمُونَ 239

And if you fear [an enemy, then pray] on foot or riding. But when you are secure, then remember Allāh [in prayer], as He has taught you that which you did not [previously] know.