It is disliked to look up at the sky during prayer; for Jabir ibn Samurah, may Allah be pleased with him, said that the Prophet, peace be upon him, said: "There will surely be some people who raise their eyes to the sky during prayer, or their sight will not return to them." In Sahih Muslim 1: 321. And Anas, may Allah be pleased with him, said that the Prophet, peace be upon him, said: "What is wrong with some people who raise their eyes to the sky during their prayers? He intensified his statement about that until he said: They must stop doing that, or their sight will be snatched away." In Sahih al-Bukhari 1: 261. See: Sharh al-Wiqayah p. 164-166, and Tabyeen al-Haqaiq 1: 162-167.