When one of you stands up to pray, he should put a screen in front of him as tall as the height of the back of a saddle. If he does not have something the height of the back of a saddle in front of him, his prayer would be invalidated if a donkey, a woman, or a black dog passed in front of him
Authentic hadithعن أبي ذر رضي الله عنه ، قال: قال رسول الله صلى الله عليه وسلم : «إذا قام أحدكم يصلي، فإنه يستره إذا كان بين يديه مثل آخرة الرحل، فإذا لم يكن بين يديه مثل آخرة الرحل، فإنه يقطع صلاته الحمار، والمرأة، والكلب الأسود»، قلت: يا أبا ذر، ما بال الكلب الأسود من الكلب الأحمر من الكلب الأصفر؟ قال: يا ابن أخي، سألت رسول الله صلى الله عليه وسلم كما سألتني فقال: «الكلب الأسود شيطان». وفي رواية من حديث ابن عباس رضي الله عنهما : «يقطع الصلاة المرأة الحائض والكلب».
Abu Dharr (may Allah be pleased with him) reported: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When one of you stands up to pray, he should put a screen in front of him as tall as the height of the back of a saddle. If he does not have something the height of the back of a saddle in front of him, his prayer would be invalidated if a donkey, a woman, or a black dog passed in front of him." I asked: “O Abu Dharr, what is the difference between a black dog and a red or a yellow dog?” He said: “O nephew, I asked the Messenger of Allah (peace and blessings of Allah be upon him) the same question and he answered: "A black dog is a devil.” According to a narration by Ibn ‘Abbās: "Prayer is invalidated by [the passing of] a menstruating woman and a dog."
Explanation
When someone stands up to pray, he should place a screen the height of the back of a saddle (approximately two-thirds of a cubit) in front of him, otherwise his prayer would be invalidated by the passing of any one of these three in front of him: a woman - restricted to a menstruating woman in the narration of Abu Dawūd - a donkey, or a black dog. However, if he places a screen in front of him, his prayer will be valid regardless of anything passing by on the other side of the screen, including those three. The narrator, ‘Abdullāh ibn As-Sāmit, asked: “O Abu Dharr: "What is the difference between a black dog and a red or a yellow dog?” Meaning: why did the Prophet (may Allah's peace and blessings be upon him) single out a black dog? He said: “O nephew, I asked the Messenger of Allah (may Allah's peace and blessings be upon him) the same question, and he answered: "A black dog is a devil.” According to the Saudi Arabian Permanent Committee for Scholarly Research and Iftā', this Hadīth means that the passing of a woman, a donkey, or a black dog in front of someone praying, renders the prayer void. However, some scholars thought that the intended meaning was that one’s focus in prayer would be interrupted or the prayer’s perfection would be compromised, rather than it would render the prayer void or invalid.
Source · Narrated by Abu Daoud - Narrated by Muslim
From the Hadith Encyclopedia (hadeethenc.com).