Does Hajj become invalidated, and must it be re-performed by someone who uttered a word of disbelief (cursing Muzdalifah) without intending thereby to curse the rituals of Allah, then pronounced the Shahada, and subsequently omitted the Dhuhr, Asr, and Maghrib prayers, combining them with Isha?

If you uttered a statement of disbelief, knowing it to be disbelief, then this is an apostasy from Islam, which invalidates the state of ihram for Hajj.

If apostasy occurs during the rituals, Hajj becomes invalid. If the Muslim repents and re-enters ihram, and manages to perform the standing at Arafat before its time expires, then their Hajj is valid. However, if it is after the time for Arafat has passed, then the Hajj is not valid.

If it was the obligatory Hajj (Hajjat al-Islam), then it must be made up. If it was a voluntary Hajj, then there is no obligation to make it up.

Apostasy invalidates the state of ihram and removes the pilgrim from it, as Allah Almighty says: ﴿If you associate others with Allah, surely all your deeds will be rendered vain﴾ (Az-Zumar: 65).

If apostasy occurs after the completion of the Hajj rituals, then the Hajj is not invalidated, because apostasy does not invalidate deeds unless one dies upon it, as Allah Almighty says: ﴿And whoever of you reverts from his religion and dies while he is a disbeliever - then those have become worthless their deeds in this world and the Hereafter, and those are the companions of the Fire; they will abide therein eternally﴾ (Al-Baqarah: 217).