Does the prayer of an individual become nullified if a devil passes in front of him, especially if he does not see it?

Taking a Sutra (barrier) and drawing near to it is legislated and recommended, for it brings about khushu' (devotion) and prevents Satan from whispering and interrupting the prayer. The intent behind the prayer being invalidated by the passing of Satan is not that it literally invalidates it, but rather it is an indication that the Sutra has an effect in achieving khushu' and preventing Satan from overpowering the servant's heart with whispers. Some scholars have interpreted the "cutting off" by Satan as referring to what passes in front of the worshipper, whether a human or something else. This "cutting off" does not necessitate the invalidation or repetition of the prayer, but rather it diminishes its perfection.