A companion of the Messenger of Allah (may Allah be pleased with him) narrates that he heard the Noble Prophet (peace and blessings be upon him) say: When any one of you is in prayer, he should not raise his gaze towards the sky, lest his sight be snatched away.
Hadith Referenceالفتح الربانی / أبواب الأذ كار الواردة عقب الصلاة / 1916