All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
A person who abandons the prayer may abandon it while denying its obligation and such a person goes out of the fold of Islam according to the consensus of the scholars, so it is not permissible to supplicate for him; or he may abandon it out of laziness, and the jurists differed in opinion about the ruling on such a person whether he is a Muslim or not as we clarified in Fataawa 81555 and 85264.
Therefore, saying that it is permissible to supplicate for him depends on whether he is a disbeliever or not. So, if we say that he is a disbeliever, it is not acceptable to supplicate for him. Shaykh Ibn ‘Uthaymeen said about the consequences of saying that a person who abandons the prayer out of laziness is a disbeliever what follows: "not washing him when he dies, not burying him with the Muslims, the prohibition of supplicating Allaah to have mercy upon him or forgive him, and the like…”
However, if we say that he is a Muslim, it is permissible to supplicate for him because he is one of the Muslims. So, whoever is of the view that he is a disbeliever, it is not permissible for him to supplicate for him, and whoever is of the view that he is a Muslim, it is permissible for him to supplicate for him.
Allaah Knows best.