Is it considered Haram not to fulfill a vow to slaughter a sheep after four years have passed, and is it permissible to fulfill it in the coming Ramadan with the intention of making up for the vow and helping the poor?

A conditional vow (Nathr Mu'allaq) is initially disliked, but its fulfillment becomes obligatory upon thealization of its condition, based on the words of Allah Almighty: "And let them fulfill their vows" (Surat Al-Hajj, 29), and the saying of the Prophet, peace and blessings be upon him: "Whoever vows to obey Allah, let him obey Him." It is permissible to delay its fulfillment if immediacy was not intended or a specific time was not set, but it is preferable to hasten its execution. If no specific recipient is designated for it, it should be given to the poor and needy. It should also be written in the will to ensure its execution after death.