Is it permissible to combine the Dhuhr prayer with the Fajr prayer in the morning due to work circumstances that might lead to missing the prayer time upon returning, and is it permissible to delay the prayer beyond its time for the same reasons, and what is the ruling on offering prayers early or delaying them, and what is the number of rak'ahs for each prayer?

It is not permissible to combine the Dawn (Fajr) prayer with the Noon (Dhuhr) prayer, even with an excuse. Rather, Dhuhr and Asr (afternoon) prayers are combined, and Maghrib (sunset) and Isha (night) prayers are combined, when there is an excuse. It is not permissible to delay the prayer beyond its prescribed time due to work. It must be performed within its time, as work is not an excuse for combining or shortening prayers. There is no good in work that causes the delay of prayer.