the dogs passion for his heart as if they had taken him away. so when he sees the dawn that is believed he is terrified because the hunters come during the day. and this second dawn is the scattered one. and from it the hadith does not mean the first dawn but the scattered one. he means the spreading light. and with its rising the white thread becomes distinct from the black thread. abu dawood said
شعف الكلاب فؤاده ، كأنها ذهبت به. فاذا رأى الصبح المصدق يفزع، لأن القناص يأتون نهارا. وهذا الفجر الثانى هو المستطير. ومنه الحديث ليس بالمستطيل يعنى الفجر الأول ولكن المستطير . يريد المنتشر الضوء. ومع طلوعه يتبين الخيط الأبيض من الخيط الأسود. قال أبو داود