Al-Ahzab 33:15

وَلَقَدۡ كَانُواْ عَٰهَدُواْ ٱللَّهَ مِن قَبۡلُ لَا يُوَلُّونَ ٱلۡأَدۡبَٰرَۚ وَكَانَ عَهۡدُ ٱللَّهِ مَسۡـُٔولٗا 15

And they had already promised Allah before not to turn their backs and flee. And ever is the promise to Allah [that about which one will be] questioned