That was on Monday evening, I don't recall the hour.
Comment:
Maopopo is a neuter verb in Hawaiian; the patient-like subject (unmarked with case morphology) is 'the hour' whereas the agent is a not a core argument marked with the objective/oblique marker (hence the verb is intransitive). The sentence may be paraphrased as 'the hour is not in the state of being known (by me)'.