امْرَأً وَنَفْسَهُ
Translation: Leave a person to himself.
امْرَأً: accusative object with an understood imperative such as “leave”.
وَ: linking wāw expressing the accompanying circumstance; accounts may differ in precise coordination/comitative analysis.
نَفْسَهُ: accusative noun, with -hu as possessive second term of iḍāfa; idiomatically “leave the person to himself”.
This is an attested idiom; the understood verb explains its sense. Its finer syntactic treatment should not be flattened into a single undisputed account.