Is it permissible to combine the Dhuhr and Asr prayers by advancing them, and the Maghrib and Isha prayers by delaying them, due to the nature of one's work, which extends for twelve hours daily, leaving the worshiper no time to rest except during the Asr, Maghrib, and Isha prayer times, knowing that if he prays the prayers at their prescribed times, he will not be able to sleep?

Drowsiness is not a permissible excuse for combining prayers. Each prayer must be performed within its prescribed time, while taking the necessary measures to stay awake. If one is overcome by sleep and unable to wake up for prayer at its appointed time, they must perform it immediately upon waking up, based on the hadith (definition): "Whoever sleeps through a prayer or forgets it, let him pray it when he remembers it." Negligence occurs while awake, not during sleep. However, intentionally sleeping before the prayer time becomes narrow, with the intention of not waking up to abandon the prayer, is a sin.