Some scholars say Muslims who don't pray are not unbelievers, but are executed: on what grounds is this justified?

A Shafi'i fiqh book states: > f1.4 A Muslim who holds the prayer to be obligatory but through lack of concern neglects to perform it until its proper time is over has not committed unbelief (dis: w18.2). Rather, **he is executed, washed, prayed over, and buried in the Muslim's cemetery** (O: as he is one of them. It is recommended, but not obligatory, that he be asked to repent (N: and if he does, he is not executed)). > *The Reliance of the Traveller*, by Ahmad ibn Naqib al-Misri (translated by Nuh Ha Mim Keller) (Here, "N:" indicates a "comment by Sheikh Nuh 'Ali Salman" and "O:" indicates an "excerpt from the commentary of Sheikh 'Umar Barakat".) Islam Q&A affirms this stance: *The Maalikis and Shaafa‘is are of the view that the one who does not pray out of carelessness and laziness, not because he denies that it is obligatory, is to be executed as a hadd punishment...*. **Question**: On what Islamic grounds is this justified? The Qur'an says: > And never is it for a believer to kill a believer except by mistake. ... But whoever kills a believer intentionally - his recompense is Hell, wherein he will abide eternally ... > Qur'an 4:92-93 And there's various hadith which talk about not killing Muslims, e.g.: > ... Abusing a Muslim is Fusuq (i.e., an evil-doing), and killing him is Kufr (disbelief). > Sahih al-Bukhari 6044 > > ... It is not permissible to kill a Muslim except in one of three cases: A adulterer who has been married, who is to be stoned; a man who kills a Muslim deliberately; and a man who leaves Islam and wages war against Allah ... > Sunan an-Nasa'i 4743 [grade: sahih] I asked a related question here: https://islam.stackexchange.com/q/40531/17163 One of the comments there suggested that it can be justified through *And do not kill the soul which Allah has forbidden [to be killed] except by [legal] right* (Qur'an 6:151 ). Thus, I would expect there to be some kind of "legal right" to execute a believer who doesn't pray.