Is the inability to wake up three hours before Fajr due to lack of time and fatigue from work considered an acceptable excuse for not fulfilling a vow made during a period of suffering from scrupulosity, knowing that the vow was made without awareness of its reprehensibility?

A Muslim must fulfill their vow, as Allah Almighty says: "And let them fulfill their vows," and the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him." However, if one is unable to fulfill it, they must offer an expiation of an oath, as the Prophet, peace and blessings be upon him, said: "The expiation for a vow is the expiation for an oath." The expiation for an oath is feeding ten needy persons or clothing them, or emancipating a slave. If one cannot find any of these, then fasting for three days. If the wording mentioned in the question is closer to a promise and not explicitly a vow, then it is not obligatory to fulfill it.