Hudhaifah ibn al-Yamaan said that Allaah’s Messenger ﷺ said: “Islaam will be effaced just as the decoration of a garment is effaced (over time), until it will not be known what fasting is, nor prayer, nor the rites of Hajj, nor charity; and one night the Book of Allaah عز وجل will indeed be taken away and not a single aayah from it will remain on earth. And some people will remain – old people – saying: ‘We found our forefathers saying this statement: laa ilaaha illallaah (none has the right to worshiped but Allaah), so we say it too.’
Then Silah bin Zufar said to Hudhaifah: ‘What help will laa ilaaha illallaah be to them when they don’t know what prayer nor fasting nor the rites of Hajj nor charity is?’ Hudhaifah turned away from him. Then Silah repeated it to him three times, and every time Hudhaifa would turn away from him. Then he turned to him on the third time and said: ‘O Silah! It will save them from the Fire’ three times.”
“This hadith contains an important benefit of fiqh: that testifying to laa ilaaha illallaah (none has the right to worshiped but Allaah) saves the one who says it (sincerely) from dwelling forever in the Fire on the Day of Resurrection, even if he didn’t use to perform any of the remaining four pillars of Islaam at all, such as prayer and so on. And it is known that the scholars have differed about the ruling on one who abandons the prayer especially while believing in its being legislated. So the majority of the scholars are of the opinion that he has not disbelieved because of that, but rather disobeyed Allaah by committing major sin; and Ahmad -in one report- was of the opinion that he has disbelieved and that he is to be killed due to apostasy not as a prescribed punishment (hadd). And it is has been authentically reported -by at-Tirmithi and al-Haakim- from the Companions that they did not consider leaving any of the actions to be disbelief except the prayer.
And I believe that the correct view is that of the majority, and that what was mentioned from the Companions is not an unequivocal text proving that they meant by ‘disbelief’ here to be the disbelief which would make the one who commits it dwell forever in the Fire and which he could not be forgiven by Allaah. How can that be when this is Hudhaifah ibn al-Yamaan -one of the foremost of those Companions- responding to Silah bin Zufar, who was about to understand the matter as Ahmad’s understanding of it and said: ‘What help will laa ilaaha illallaah be to them when they don’t know what prayer is. . .’ then Hudhaifa replied to him after his turning away from him: ‘O Silah! It will save them from the Fire’ three times. So this is an unequivocal text from Hudhaifah proving that one who abandons the prayer -and likewise the other (three) pillars- is not a disbeliever but rather a Muslim who will be saved from dwelling forever in the Fire on the Day of Resurrection. So remember this, for you may not find it in other than this place.”
 Saheeh at-Tirmithi 2622
[silsilat ul-ahaadeeth is-saheehah 87 / alalbaany.com]