Surah Al-Baqarah (The Cow), Verse 239

فَاِنْ خِفْتُمْ فَرِجَالًا اَوْ رُكْبَانًا فَاِذَاۤ اَمِنْتُمْ فَاذْكُرُوا اللّٰهَ كَمَا عَلَّمَكُمْ مَّا لَمْ تَكُوْنُوْا تَعْلَمُوْنَ ۟

Fa in khiftum farijaalan aw rukbaanan fa izaaa amintum fazkurul laaha kamaa 'allamakum maa lam takoonoo ta'lamoon

“If ye fear (an enemy), pray on foot, or riding, (as may be most convenient), but when ye are in security, celebrate Allah's praises in the manner He has taught you, which ye knew not (before).”

Quran 2:239 (Yusuf Ali Translation)