I do not think that the labour law distinguishes Muslim and non-muslim. It states that each Employee shall work two hours less each day during the holy month of ramadan.
FEDERAL LAW NO. (8) OF 1980
LABOUR LAW AND ITS AMENDMENTS
CHAPTER IV
WORKING HOURS AND LEAVES
SECTION 1
WORKING HOURS
ARTICLE (65)
The maximum normal working hours for adult employees shall be eight hours per day or forty eight hours per week. However, working hours for the employees of commercial establishments, hotels, restaurants, watchmen and similar operations may be increased to nine hours per day as determined by the Minister of Labour. Likewise, working hours per day in respect of hazardous work or work detrimental to health, may be decreased by decision of the Minister of Labour and Social Affairs. During the month of Ramadan, normal working hours shall be reduced by two hours.
Time spent by the employee in transport form his residence to the place of work shall not be included in the working hours.