Is delaying the prayer until a very faint light from the sun appears – before the yellowness becomes apparent – considered as missing its time and entering into the major sins, and is this intense fear of missing the prayer time considered a whisper (waswasa)?

The time for Fajr prayer ends with sunrise, according to the majority of scholars. What is meant by sunrise is the beginning of the appearance of its disk. It is disliked to delay Fajr prayer until that time without an excuse; rather, it may even be forbidden. One must strive to perform the prayer on time, taking the necessary steps to help awaken, and whoever does not wake up is not sinful, based on the Prophet, peace and blessings be upon him, who said: "There is no negligence in sleep." The mere eagerness for prayer and fear of missing its time is not considered a whisper [of Satan/obsessive thought].