• One piece of evidence that somebody who abandons prayer is a disbeliever is that Allāh, Exalted is He, says, “But if they repent, establish prayer, and give zakah, then they are your brothers in religion; and We detail the verses for a people who know. [Sūrat Al Tawbah, Āyah no. 11]. Sheikh Al ‘Uthaymīn said that this Āyah is evidence because Allāh sets three conditions for brotherhood to be established between us and polytheists:

1. That they repent from shirk (polytheism)
2. That they pray
3. That they pay zakāt (Islamic poor due)

[Sheikh Al ‘Uthaymīn, Ḥukm Tārik Al-Ṣalāt (Rulings regarding those who abandon prayer), p.6]

• One piece of evidence that somebody who abandons prayer is a disbeliever is that Allāh, Exalted is He, says, “But there came after them successors who neglected prayer and pursued desires; so they are going to meet evil -Except those who repent, believe and do righteousness; for those will enter Paradise and will not be wronged at all.” [Sūrah Maryam, Āyah nos. 59-60]. The point in the Āyahs being that Allāh says, regarding those who follow their desires and do not pray, “Except those who believe”, which shows that if they follow their desires and do not pray, they are not believers. [Sheikh Al ‘Uthaymīn, Ḥukm Tārik Al-Ṣalāt (Rulings regarding those who abandon prayer), p.5].
• The evidence for the ruling regarding the one who abandons prayer includes the fact that that the Messenger (May Allāh praise him and Peace be upon him) said, “What separates a man from kufr (disbelief) or shirk (polytheism) is abandoning prayer” [Reported by Imam Muslim: 987].
• Another piece of evidence that somebody who abandons prayer is a disbeliever is that the Messenger (May Allāh praise him and Peace be upon him) said, “The contract that exists between us and them is prayer. So, whoever abandons the prayer has disbelieved” [Reported by Imam Aḥmad: 5/346].
• Buraydah Bin Al Haṣīb (may Allāh be pleased with him) said, “I heard Allāh’s Messenger (May Allāh praise him and Peace be upon him) say, “The contract that exists between us and them is prayer. So, whoever abandons prayer has disbelieved”. Sheikh Al ‘Uthaymīn (may Allāh have mercy on him) said, “The type of disbelief referred to here is the type that takes the person out of the fold of Islam, because the Prophet (May Allāh praise him and Peace be upon him) declared prayer something that distinguishes believers from disbelievers, and the fold of disbelief is clearly not the fold of Islam. So, whoever does not fulfil the contract is a disbeliever. [Sheikh Al ‘Uthaymīn, Ḥukm Tārik Al-Ṣalāt (Rulings regarding those who abandon prayer), p.9].