Is leaving the 'Isha prayer and sleeping through it, then making it up the following day, considered a violation of a vow never to abandon prayer, knowing that the intention was never to completely forsake prayer?

Prayer holds a great status in Islam; it is the second pillar after the two testimonies, and the first act to be considered. Neglecting it is a grave sin, and severe warnings have been mentioned concerning it: (So woe to those who pray, [But] who are heedless of their prayer) and (Then succeeded them a posterity who neglected prayers and pursued desires; so they are going to meet evil). Repentance is obligatory, as well as adherence to prayer in the future, and frequent seeking of forgiveness and good deeds. As for vows concerning prayer, such a vow is not valid and does not necessitate expiation, because vowing an obligation is a mere formality. A conditional vow is not binding unless the condition upon which it is contingent is met.