The messenger of Allah ﷺ said: "When anyone of you stands to pray, then he is screened if he has in front of him something as high as the back of a camel saddle. If he does not have something as high as the back of a camel saddle in front of him, then his prayer is nullified by a woman, a donkey or a black dog." I (one of the narrators)said: "What is the difference between a black dog, a yellow one and a red one?" He said: I asked the Messenger of Allah ﷺ just like you and he said:"The black dog is a shaitan." (Using translation from Nasāʾī 750)
قَالَ رَسُولُ اللهِ ﷺ «إِذَا كَانَ أَحَدُكُمْ قَائِمًا يُصَلِّي فَإِنَّهُ يَسْتُرُهُ إِذَا كَانَ بَيْنَ يَدَيْهِ مِثْلُ آخِرَةِ الرَّحْلِ فَإِنْ لَمْ يَكُنْ بَيْنَ يَدَيْهِ مِثْلُ آخِرَةِ الرَّحْلِ فَإِنَّهُ يَقْطَعُ صَلَاتَهُ الْمَرْأَةُ وَالْحِمَارُ وَالْكَلْبُ الْأَسْوَدُ» قُلْتُ مَا بَالُ الْأَسْوَدِ مِنَ الْأَصْفَرِ مِنَ الْأَحْمَرِ؟ قَالَ سَأَلْتُ رَسُولَ اللهِ ﷺ كَمَا سَأَلَتْنِي فَقَالَ «الْكَلْبُ الْأَسْوَدُ شَيْطَانٌ»