AL BAQARAH — Ayat 239

فَإنْ خِفْتُمْ فَرِجَالاً أَوْ رُكْبَانًا فَإِذَا أَمِنتُمْ فَاذْكُرُواْ اللّهَ كَمَا عَلَّمَكُم مَّا لَمْ تَكُونُواْ تَعْلَمُونَ

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