What is the ruling on glancing aside in the prayer?

Question

If someone during the prayer looks to another side in such a way that he does not move his neck, that is, does not turn his head — is his prayer lost or does it remain [valid]?

Answer

The prayer does not become fasid (invalid) because of this; it is, however, contrary to what is mustahabb (khilaf al-istihbab).

Source: Fatawa Mahmudiyya

Preview. The full text opens with JavaScript enabled.