Question: What is the ruling concerning the one who performs Hajj whilst he has abandoned prayer, either intentionally (because he believes he doesn’t have to) or due to neglect? Is his Hajj acceptable?
Response: Whoever performs the Hajj whilst he does not pray because he believes it is not obligatory, then he has committed kufr by consensus and his Hajj is not accepted. However, if he does not pray out of laziness and neglect, then in this (case) there is a difference of opinion amongst the people of knowledge. From amongst them are those who view his Hajj as correct, and (likewise there are) those who view his Hajj as incorrect. And that which is correct is that it is not accepted for that which the Prophet (sal-Allaahu `alayhe wa sallam) said:
((The covenant that is between us and them [the disbelievers] is the prayer. Whoever abandons it has committed kufr)),
and He (sal-Allaahu `alayhe wa sallam) also said:
((Between a man and disbelief and polytheism is the abandoning of the prayer)).
And this is general and encompasses both one who believes it is not obligatory and one who does not pray out of laziness or neglect.
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet (sal-Allaahu `alayhe wa sallam) and his family and his companions.
Shaykh Ibn Baaz
Fataawa al-Hajj wal-‘Umrah waz-Ziyaarah – Page 15.fatwaonline.com