What objects or persons passing in front of a praying person invalidate the prayer?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
The well-established view from Imam Ahmad is that nothing invalidates the prayer except for the utterly black dog (al-kalb al-aswad al-bahim). This view is attributed to Aisha and Ta'us. The reasoning offered is that the utterly black dog is a devil. The text specifies that 'bahim' means a color that has no other color mixed with it. If the dog is black but not entirely black (i.e., has other colors mixed in), it does not invalidate the prayer because the text specified 'bahim'. If the utterly black dog has two white spots between its eyes, it is still considered utterly black and subject to the rulings of cutting the prayer, prohibition of hunting it, and permissibility of killing it, based on the hadith mentioning the utterly black one with two white markings ('dhū al-ghurratayn').
Supporting text
A dissenting opinion from Ahmad, one narration, holds that the black dog, a woman passing, and a donkey invalidate the prayer. Another view, held by Aisha, suggests that the ruling concerning the passing person only applies when the passerby is not pausing, and that voluntary prayer is easier than obligatory prayer. Some scholars argue that the hadith mentioning the woman, donkey, and dog passing is not conclusive because the passerby is momentary and the obligation of the obligatory prayer is stricter. A third position, held by Urwah, Shabi, Thawri, Malik, Shafi'i, and the Companions of Ra'y, is that nothing invalidates the prayer, citing the hadith, 'Nothing cuts the prayer.' However, the primary established view prefers the hadith that specifically mentions the utterly black dog as being more authentic and particular.