Is it permissible not to perform Fajr prayer at its appointed time, for fear of waking a sick husband who needs to sleep and should not be awakened?

The time for Fajr prayer begins with the true dawn (Al-Fajr Al-Sadiq) and ends with sunrise. There is no harm in praying it before its time expires. However, delaying it beyond its time is not permissible except for a valid excuse. The husband's illness is not an excuse. The woman can pray Fajr quietly without waking her husband. If the husband is ill and has lost his mental faculties, he is not obligated to pray. However, if he is of sound mind, he is obligated to pray, and there is a difference of opinion regarding the obligation to wake him for it.