Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "What is wrong with people that they raise their gaze towards the sky in their prayer?" Then he (peace and blessings be upon him) spoke sternly: "They must certainly desist from this (act), or their sight will be snatched away."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3536