فَعَلْتُهَا إِذًا وَأَنَا مِنَ الضَّالِّينَ
I did it then while I was among those who did not know the full right course. (al-Shuʿarāʾ 26:20)
In examining the account of Moses and the Egyptian, commentators distinguish the period before his prophetic mission, the intention behind the blow, and the possible meanings of the Arabic term ḍāllīn. It is not valid to assume without analysis that the term necessarily asserts religious unbelief or deliberate murder.
A moral and legal analysis of an incident requires attention to intention, circumstances and the individual's status at the time, not just to the resulting event.