وَلَقَدْ كَانُوا۟ عَـٰهَدُوا۟ ٱللَّهَ مِن قَبْلُ لَا يُوَلُّونَ ٱلْأَدْبَـٰرَ ۚ وَكَانَ عَهْدُ ٱللَّهِ مَسْـُٔولًا Qur’an Al-Ahzab (33:15)Walaqad k a noo AA a hadoo All a ha min qablu l a yuwalloona aladb a ra wak a na AAahdu All a hi masool a n
Apparently, after the battle of Uhud, certain men who had then shown cowardice were forgiven on undertaking that they would behave better next time. A solemn promise made to the Messenger of Allah is a promise to Allah, and it cannot be broken with impunity.