Hadith: What is the matter with some people who raise their eyes towards the sky during their prayer? He went on, using a strict language: They must refrain from that action, or else their sights will certainly be snatched away

عن أنس بن مالك رضي الله عنه قال: قال النبي صلى الله عليه وسلم : «ما بَال أقْوَام يَرفعون أبْصَارَهم إلى السَّماء في صَلاتهم»، فاشْتَدَّ قوله في ذلك، حتى قال: «لَيَنْتَهُنَّ عن ذلك، أو لَتُخْطَفَنَّ أبْصَارُهم».
[صحيح] - [متفق عليه]

Anas ibn Mālik (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) said: What is the matter with some people who raise their eyes towards the sky during their prayer? He went on, using a strict language: They must refrain from that action, or else their sights will certainly be snatched away.
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

This Hadīth teaches us how the praying person should be in his prayer, namely, he should be in a state of tranquility and submissiveness. Among the signs of the submissiveness of the heart is the body organs being tranquil. For this reason, the Prophet (may Allah's peace and blessings be upon him) warned his nation against engaging in useless acts during the prayer, such as raising one's eyes toward the sky. This is something that is contrary to the etiquette and status of the prayer, because during prayer, the person is communicating privately with his Lord who is before him in the direction of Qiblah. So, raising one's eyes is considered an act of impoliteness with Allah. Hence, the Prophet (may Allah's peace and blessings be upon him) stressed this point with a firm and stern warning. He warned such people from raising their eyes towards the sky while praying, stating that they would either refrain from doing so, or their eyesight would be snatched away, in such a way that they would suddenly lose the blessing of eyesight as a result of their negligence and disrespect of the prayer.