Al-Hasan al-Basri (may Allah have mercy on him) was asked about a man who frightens another so much that he loses his intellect altogether. He said: If Sayyiduna Umar (may Allah be pleased with him) had come across such a person, he would certainly have taken the diyah from him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16232