With regard to missing prayers, one of the following two scenarios must apply:
1 – When you miss a prayer unintentionally, for a legitimate shar’i excuse, such as forgetting or sleeping, although you are basically very keen to perform the prayer on time. In this case you are excused but you have to make it up as soon as you remember it. The evidence for that is the hadeeth narrated in Saheeh Muslim (681) which tells how the Prophet (peace and blessings of Allaah be upon him) and his companions slept and missed Fajr prayer, and the Sahaabah began to ask one another, “What is the expiation (kafaarah) for what we have done by neglecting the prayer?” The Messenger of Allaah (peace and blessings of Allaah be upon him) said. “Sleeping does not mean that you are neglecting the prayer. Rather neglecting the prayer means not praying one prayer until the time for the next prayer comes. Whoever does that let him pray when he remembers it.”
This does not mean that a person should sleep deliberately when a prayer is due, until he misses it, then use sleep as an excuse, or neglect a means that would help him to do the prayer, and then take that as an excuse. Rather he must make use of all the means he can, as the Messenger (peace and blessings of Allaah be upon him) did in this case, when he appointed one person to stay awake and wake them up to pray, but that person was overcome by drowsiness, so he did not wake them up. This is the case in which a person may be excused.
2 – When you miss a prayer deliberately. This is a major sin, and it is so serious that some of the scholars stated that the one who does this is a kaafir. (as it says in Majmoo’ Fataawa wa Maqaalaat Samaahat al-Shaykh Ibn Baaz, 10/374). The one who does this has to repent sincerely, according to scholarly consensus. With regard to making up the prayer, there was a difference of opinion among the scholars as to whether or not it would be accepted from him if he makes it up afterwards. Most of the scholars said that he should make it up and that his prayer is valid, although he is a sinner (i.e., if he does not repent – and Allaah knows best), as Shaykh Ibn ‘Uthyameen quoted from them in al-Sharh al-Mumti’, 2/89. The view favoured by Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) is that it is not valid, and that it is not prescribed for him to make it up. He said in al-Ikhtiyaaraat (34): “It is not prescribed for the one who misses a prayer deliberately to make it up, and the prayer, if he makes it up, is not valid; rather he should do a lot of voluntary (naafil) prayers. This is the view of a group among the Salaf.” One of the contemporary scholars who regarded this view as more correct is Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him); he quoted as evidence for that the words of the Prophet (peace and blessings of Allaah be upon him), “Whoever does an action that is not in accordance with this matter of ours (i.e., Islam), will have it rejected.” (Agreed upon).
So you must beware of this and strive to perform all the prayers on time, as Allaah says (interpretation of the meaning):
“Verily, As‑Salaah (the prayer) is enjoined on the believers at fixed hours”
[al-Nisa’ 4:103]
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