The ruling on the Fast of the Person who sleeps on the Job
Question :
There is an employee who says that he has slept more than once on the job and did not do his work. Did he corrupt his fast in doing so?
Answer:
His fast is not corrupted, because there is no relationship between not doing work and the fast. However, it is obligatory on the person who is assigned a job to perform the job that he has been entrusted with. This is because he takes pay and a salary for this work. It is obligatory that his work be done in a manner that will free him of any liability, just as he expects his entire salary. However, the reward for his fast is lessened due to his doing something forbidden, which is his sleeping on the job that has been entrusted to him.
Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 3 Page 281