"The same has statutory basis in Section 3 (a) of P.D. No. 291, as amended by P.D. No. 322, which categorically states that [d]uring the fasting season in the month of Ramadan, all Muslim employees in the national government, government-owned or controlled corporations, provinces, cities, municipalities and other instrumentalities shall observe office hours from seven-thirty in the morning (7:30 a" . . . . . .