Is Prayer Accepted From One Who Drinks Alcohol?
Question

Is the report narrated from the Messenger of Allah Muhammad (peace and blessings of Allah be upon him), which says that whoever drinks alcohol, his prayers will not be accepted for a period of forty days, authentic?
Praise be to Allah.There are many authentic Hadiths concerning the punishment for one who drinks alcohol which say that his prayers will not be accepted for forty days. This was narrated from `Amr ibn Al-`As, Ibn `Abbas, Ibn `Umar and Ibn `Amr (may Allah be pleased with them). (See As-Silsilah As-Sahihah, 709, 2039, 2695, 1854)
One of these Hadiths was narrated by Ibn Majah (3377) from `Abdullah ibn `Amr (may Allah be pleased with him) who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “Whoever drinks alcohol and gets drunk, his prayer will not be accepted for forty days and if he dies he will go to Hell. But if he repents, Allah will accept his repentance. If he again drinks alcohol and gets drunk, his prayer will not be accepted for forty days and if he dies he will go to Hell. But if he repents, Allah will accept his repentance. If he again drinks alcohol and gets drunk, his prayer will not be accepted for forty days and if he dies he will go to Hell. But if he repents, Allah will accept his repentance. If he commits (this sin) again, then Allah pledges to make him drink the mud of Khabal on the Day of Resurrection.” They asked, “O Messenger of Allah, what is the mud of Khabal?” He said, “The juices of the people of Hell.” (Classed as authentic by Al-Albani in Sahih Ibn Majah) 
The fact that his prayers are not accepted does not mean that they are not valid, or that he should give up praying, rather it means that he will not be rewarded for them. 
So the benefit of praying will be that he will have discharged his duty and will not be punished for not doing it. 
Abu `Abdullah ibn Mandah (may Allah have mercy on him) said: “The words “his prayer will not be accepted” mean that he will not be rewarded for his prayer for forty days, as a punishment for his drinking alcohol , just as they say that the one who speaks on Friday when the Imam is delivering the Khutbah should pray Jumu`ah but there is no Jumu`ah for him, meaning that he will not be given the reward for Jumu`ah as a punishment for his sin.” (Ta`thim Qadr As-Salah, 2/587, 588) 
An-Nawawi (may Allah have mercy on him) said: 
“With regard to his prayer not being accepted, what this means is that he will not be rewarded for it, even though it is valid in the sense that he has discharged his duty and does not need to repeat it.” 
No doubt the person who drinks alcohol still has to perform the prayers on time. If he were to delay any of his prayers , he would be committing a grave major sin, which is worse than the sin of drinking alcohol . 
This punishment for drinking alcohol applies to the one who does not repent. But if he repents to Allah and turns to Him, He will accept his repentance and accept his good deeds, as it says in the Hadith quoted above: “… but if he repents, Allah will accept his repentance.” And the Prophet (peace and blessings of Allah be upon him) said: “The one who repents from sin is like one who did not commit sin.” (Narrated by Ibn Majah, 4250; classed as sound by Al-Albani in Sahih Ibn Majah) 
And Allah knows best.