Muhammad said: The meaning of "they pursued them" is: they caught up with them. It is said: "ashraqna" (we entered the sunrise), meaning: we entered into the time of sunrise, just as one says "amsayna" (we entered the evening) and "asbahna" (we entered the morning): meaning we entered into the evening and the morning. It is also said: "sharuqat al-shamsu" when it rises, and "ashraqat" when it shines and clears.
قَالَ مُحَمَّد: معنى ﴿اتَّبَعُوهُمْ﴾: لَحِقُوهُمْ، وَيُقَالُ: أَشْرَقْنَا؛ أَيْ: دَخَلْنَا فِي الشُّرُوقِ؛ كَمَا يُقَالُ: أَمْسَيْنَا وَأَصْبَحْنَا: دَخَلْنَا فِي الْمَسَاءِ وَالصَّبَاحِ، وَيُقَالُ: شَرُقَتِ الشَّمْسُ إِذَا طَلَعَتْ، وأشرقت إِذا أَضَاءَت وصفت.