Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:8:16 –

And whoever turns his back to them on such a day, unless swerving ˹as a strategy˺ for war or joining ˹another˺ company, has certainly returned with anger ˹upon him˺ from Allah, and his refuge is Hell - and wretched is the destination.  

Whoever turns his back to them on that day, the day of the encounter with them, unless manœuvring, turning around, for battle — by pretending to be in flight, as a trick, while actually intending to relaunch an attack — or joining another detachment, a company of Muslims, calling on it for assistance, he has truly incurred the wrath of God, and his abode will be Hell — an evil journey’s end!, ˹an evil˺ return it is. This ˹threat˺ applies so long as the ˹numbers of˺ disbelievers do not surpass twice ˹that of the believers˺.
القرآن:٨:١٦ –

وَمَنْ يُوَلِّهِمْ يَوْمَئِذٍ دُبُرَهُ إِلَّا مُتَحَرِّفًا لِقِتَالٍ أَوْ مُتَحَيِّزًا إِلَىٰ فِئَةٍ فَقَدْ بَاءَ بِغَضَبٍ مِنَ اللَّهِ وَمَأْوَاهُ جَهَنَّمُ ۖ وَبِئْسَ الْمَصِيرُ  

{ومن يولهم يومئذ} أي يوم لقائهم {دُبُرَهُ إلا متحرفا} منعطفا {لقتال} بأن يريهم الغرَّة مكيدة وهو يريد الكرَّة {أو متحيزا} منضما {إلى فئة} جماعة من المسلمين يستنجد بها {فقد باء} رجع {بغضب من الله ومأواه جنهم وبئس المصير} المرجع هي وهذا مخصوص بما لم يزد الكفار على الضعف.