Question [Reader]:
Someone with a question is saying: Esteemed Shaikh, I miss the Fajr prayer often, and I don’t pray [it] except after sunrise at the time I want to go to work. And this matter might happen again and again, so is there any [sin] upon me? And What should I do in order to stick to my prayer on time?
Shaykh Muhammad ibn Saalih Al-‘Uthaymeen:
Do a number of things.
The first thing is that you sleep early. That you sleep early. And it is for this reason the Prophet sallallaahu alaihi wa sallam used to hate [one’s] sleeping before Eshaa’ and enganging in discussions after it so that a person may go to sleep early in order to wake up early. This is one.
Second is that you have an intention at the time of going to sleep. a resolve, and determination that you are going to wake up for Fajr prayer. Then waking up will be easy for you.
Third is that you use an alarm clock you put by your head that sets off an alarm for you. And if you’re afraid that when it goes off, you’ll switch it off, turn off the sound, and keep sleeping, keep it away from you a bit. And someone, out of concern for the prayer, would put the alarm clock in a tin can [words unclear] and keep it at a distance from himself, so that it would have a powerful sound, so he would wake up. Do this. There’s nothing prohibiting [it].
If this weren’t easy for you, put a telephone by your head, if you have a telephone, and tell one of your brothers, “When the Adhaan for Fajr is given, give me a ring.” What’s important is that a person can do things which result in his waking up so that he can perform Fajr in its time. And one who makes laziness a habit for himself will remain upon laziness.
(voices too faint to hear requesting further clarification from the Shaikh)
As for prayer in other than its time, if one intended [that], then the prayer is not accepted. It is rejected from him, even if he were to pray it a thousand times, due to the saying of the Prophet , Whoever does an act that is not under our legislation, it will be rejected,“ meaning it is returned back to him [unaccepted].
Source: http://salaf-us-saalih.com/2015/08/08/i-miss-the-fajr-prayer-often-what-should-i-do/