Is it obligatory to perform Hajj with the reserved money allocated for emergencies, knowing that it is sufficient to cover the expenses of Hajj, or is it permissible to keep it for its original purposes and avoid financial strain?

Capability is a condition for the obligation of Hajj, and it includes financial ability, by the pilgrim providing the costs and expenses of Hajj for going and returning, and the expenses of those whose maintenance is his responsibility, and settling debts, and owning what exceeds his basic needs. And whoever meets these conditions, Hajj becomes obligatory upon him, and the fear of poverty or future need does not waive it, for Allah replaces what is spent by those who spend.