The 8 volume work entitled "Fatawa Islamiyyah" Vol.2 page 371 published by Dar us Salaam Publishers:
"A husband (or wife) who does not pray is a disbeliever, according to the words of the Prophet s.a.a.w.: "The covenant which is between us and them is the prayer, and whoever abandoned it, has disbelieved." (At-Tirmithi, An-Nasa'i and Ahmad) and also: "Between a man and disbelief and shirk is abandoning the prayer." (Muslim). Whether or not he denies its obligation. If he does deny its obligation, he is a disbeliever according to the consensus of scholars. And if he abandons it due to negligence and laziness, but does not deny its obligation, he is also a disbeliever according to the most authoritative sayings of the scholars based upon the two aforementioned hadiths and other reports which carry the same meaning." Bin Baz
Volume 2 of same book pgs 368-69:
As for the saying of the Companions, the majority of them, indeed, more than one reported that all of them regarded the one who abandons the prayer as a disbeliever. Abdullah bin Shaqiq said: "The Companions of the Prophet s.a.a.w. did not regard the abandonment of anything to be disbelief except for prayer." And Imam Ishaq bin Rahwayh, the famous scholar said: "It has been authentically reported from the Prophet s.a.a.w. that the one who abandons prayer is a disbeliever." Ibn Hazm mentioned that it has been reported from Umar, Abdur-Rahma bin Awf, Mu'ath bin Jabal, Abu Hurairah and others from among the Companions, and he said, "And we know of no one among the Companions who contradicts them."