Hadith 1754 - Bab 340 (Prohibition of raising one's Eyes towards the sky during As-Salat (The Prayer))
Chapter 18 (The Book of the Prohibited actions)

Anas bin Malik (May Allah be pleased with him) said: The Messenger of Allah (Peace be upon him) said, "How is it that some people raise their eyes towards the sky during As-Salat (the prayer)?" He stressed (this point) and added, "People must refrain from raising their eyes towards heaven in Salat (prayer), or else their sights will certainly be snatched away."

[Al-Bukhari].

Selon Anas Ibn Mâlek (das), le Messager de Dieu (bsdl) a dit: «Qu"ont donc certaines gens à lever leurs regards vers le ciel durant la prière?» Il ne cessa pas de leur reprocher durement la chose jusqu"à dire: «Ou bien ils cessent de le faire, ou bien Dieu leur enlèvera sûrement la vue». (Rapporté par Al Boukhâri)