"O you who have believed, when you meet those who disbelieve in a battle formation," Muhammad said: The zahf (battle formation) is a group that advances toward their enemy in one go—meaning: they descend upon them. The term zahf can also be an infinitive from your saying: 'I advanced' (zahaftu).
"And do not turn your backs to them," meaning: do not flee.
﴿يَا أَيهَا الَّذِينَ آمَنُوا إِذَا لَقِيتُمُ الَّذِينَ كفرُوا زحفاً﴾ قَالَ مُحَمَّدٌ: الزَّحْفُ جَمَاعَةٌ يَزْحَفُونَ إِلَى عَدُوِّهِمْ بِمَرَّةٍ - أَيْ: يَنْقَضُّونَ - وَقَدْ يَكُونُ الزَّحْفُ مَصْدَرًا مِنْ قَوْلِكَ: زَحَفْتُ.
﴿فَلا تُوَلُّوهُمُ الأَدْبَارَ﴾ أَي: لَا تنهزموا
