What is the ruling on one who misses the Fajr prayer despite taking measures to perform it, and is he considered a disbeliever if he adopts the view of those who declare the one who abandons prayer to be a disbeliever? And what is the way to avoid missing it, while still being able to stay up late in obedience to Allah?

Taking the means to wake up for Fajr prayer is recommended, and some say it is obligatory. Whoever takes these means and then is overcome by sleep incurs no sin and must pray when they wake up. If you become aware after the time for prayer has begun, it is not permissible to sleep again unless you are reasonably certain you will wake up before the time expires. However, if you are reasonably certain you will not wake up in time and you deliberately choose to sleep, you have sinned and repentance is obligatory. Do not assume you will not wake up if you sleep; rather, do what you can and do not burden yourself with what you cannot bear. If you miss the prayer without negligence, there is no sin upon you. Combining staying up late in obedience and being attentive to Fajr prayer is possible through striving and supplication. If they conflict, performing Fajr prayer at its appointed time is more paramount.