Praise be to Allah.
Not performing one’s prayers is a dereliction of the most important duty among the pillars of Islam. Prayer is the pillar and cornerstone of the faith, and it is not permissible under any circumstances to be lenient towards the one who is not praying. First of all his family should advise and enjoin him to pray, then they should boycott him and turn away from him, and not greet him with salaam, or eat with him or sit with him, in order to point out to him the seriousness of sin, so that he will come back to Allaah and repent. The opinions of the scholars with regard to the one who does not pray may be summed up under the following two headings:
1.The opinion that the one who does not pray is a kaafir, which is the opinion narrated from ‘Umar, ‘Ali and Ibn Mas’ood (may Allaah be pleased with them). It was also the opinion of al-Hasan, al-Sha’bi, al-Oozaa’i, Ibn al-Mubaarak and Muhammad ibn al-Hasan; it was also reported from Ahmad, and is indicated by the hadeeth of the Prophet (peace and blessings of Allaah be upon him), “All that stands between a person and kufr is his not praying.” (Reported by Muslim, Ahmad, Abu Dawood and Ibn Maajah).
2.The opinion that the one who does not pray is not a kaafir. This is the opinion of Abu Haneefah, Maalik, and al-Shaafa'i, and is indicated by the hadeeth of ‘Ubaadah ibn al-Saamit, who reported that the Prophet (peace and blessings of Allaah be upon him) said: “There are five prayers which Allaah has prescribed for His slave during the day and night, whoever does them and does not wilfully neglect them, Allaah will be bound to grant him admittance to Paradise. Whoever does not do them will have no such guarantee; if He wills, He will punish him and if He wills, He will grant him admittance to Paradise.” (Reported by al-Daarimi, 1531; Maalik, al-Muwatta’, 248; Ahmad, 21690).
However, according to both opinions, if a person insists on not praying, he should be asked three times to repent, and if he refuses, then his fate will be execution.