What is the ruling on praying Fajr before sunrise, or during it, or two hours or more after it, and is this prayer valid?

The time for Fajr prayer ends when the sun rises, by scholarly consensus. It is not permissible to intentionally delay it until the sun rises, as that is a great sin and a major transgression. There is no sin in delaying it as long as the sun has not risen, even though it is preferable to perform it in the darkness before dawn (al-ghalas). As for delaying it intentionally or due to negligence, it is a major sin that necessitates repentance, though the prayer itself is valid in all cases. The one excused by sleep or forgetfulness bears no sin, and their time for prayer is when they wake up or remember, while it is necessary to take precautions to wake up.