he was praying and a son a Marwan wanted to pass in front of him. He tried to stop him but he did not go back, so he hit him. The boy went the boy went out crying and went to Marwan and told him (what had happened). Marwan said to Abu Sa'eed: "Why did you hit your brother's son?" He said: "I did not hit him, rater I hit the Saitan. I heard the Messenger of Allah say: 'If one of you is praying and someone wants to pass in front of him, let him troy to stop him as much as he can, and if he persists then let him fight him, for he is a devil. (Using translation from Nasāʾī 4862)  

أَنْ يَمُرَّ بَيْنَ يَدَيْهِ فَدَرَأَهُ فَلَمْ يَرْجِعْ فَضَرَبَهُ فَخَرَجَ الْغُلَامُ يَبْكِي حَتَّى أَتَى مَرْوَانَ فَأَخْبَرَهُ فَقَالَ مَرْوَانُ لِأَبِي سَعِيدٍ لِمَ ضَرَبْتَ ابْنَ أَخِيكَ؟ قَالَ مَا ضَرَبْتُهُ إِنَّمَا ضَرَبْتُ الشَّيْطَانَ سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ «إِذَا كَانَ أَحَدُكُمْ فِي صَلَاتِهِ فَأَرَادَ إِنْسَانٌ يَمُرُّ بَيْنَ يَدَيْهِ فَلْيَدْرَأْهُ مَا اسْتَطَاعَ فَإِنْ أَبَى فَلْيُقَاتِلْهُ فَإِنَّهُ شَيْطَانٌ»  

“The Messenger of Allah ﷺ said: ‘Whoever gives medical treatment, with no prior knowledge of medicine, is responsible (for any harm done).’” (Using translation from Ibn Mājah 3466)  

قَالَ رَسُولُ اللهِ ﷺ «مَنْ تَطَبَّبَ وَلَمْ يُعْلَمْ مِنْهُ طِبٌّ قَبْلَ ذَلِكَ فَهُوَ ضَامِنٌ»