Assalamu Alaikum wa Rahmathullahi wa Barakathuhu!
What do the respected Ulama say about those who do not perform Namaz? Are they Kafirs? What do the guided Imams say about this?
Let it be known that, a person's mere non-performance of Salat only is not the indication or reason for his leaving Islam and entering Kufr, rather, it is not correct to apply the ruling of Kufr on a person, after accepting Islam, until he bears an explicit Kufr concept or utters an explicit Kufr talk. Similarly a person who admits the obligation of Salat but due to some laziness or short-comings does not perform it, is undoubtedly a sinner for leaving the Salat but declaring him as Kafir is a wrong and impermissible act, refraining from which is essential. As for reference made on those Ahadees e Mubaraka, such a person is called so as a matter of warning and not in its real essence.
Allah knows best.