What should I do about my husband who delays Fajr prayer until he leaves for work, knowing that he prays the other prayers on time, and that my attempts to wake him up cause big problems between us, which made me stop waking him up?

Sleeping before the prayer time begins is permissible, even if it leads to missing the prayer. In this case, some scholars believe that it is not obligatory to wake the sleeper, but rather desirable if no harm is feared. Others, however, hold that it is obligatory to wake him because it falls under the category of changing an evil (munkar), and this obligation is waived only if there is certainty or strong presumption that considerable harm will result or that the person will become more defiant.