Is the reward for one who prays Fajr on time after staying up all night working the same as the reward for one who wakes up for it after sleeping during the day? And is it permissible to combine Dhuhr and Asr prayers with Maghrib due to the nature of night work and daytime sleep?

The reward for an act of worship varies according to the hardship involved, as the Prophet, peace and blessings be upon him, said: "Indeed, your reward is commensurate with your effort." It is not permissible to combine two prayers for the sake of sleep; rather, one must perform the prayer at its appointed time and then return to sleep. Whoever strives to perform prayers at their proper times despite hardship will have a great reward. The Maghrib prayer is not combined with Asr; it is only combined with Isha when there is a valid excuse permitting combination, such as travel or rain.