"And the companions of the left—what are the companions of the left?" They are those who are ominous/ill-fated for themselves.
Muhammad said: His saying: "What are the companions of the right?" This expression in Arabic follows the flow of astonishment, as if He were saying: What are they? It is said in speech: "So-and-so, what is so-and-so?" Its usage from Allah, the Mighty and Majestic, in addressing the servants is in the manner of that which elevates their status in their estimation, and likewise is this in His saying: "What are the companions of the left?" meaning: What are they?
﴿وَأَصْحَابُ الْمَشْئَمَةِ مَا أَصْحَابُ الْمَشْئَمَةِ﴾ وهم المشائيم على أنفسهم.
قَالَ محمدٌ: قَوْله: ﴿مَا أَصْحَابُ الْمَيْمَنَةِ﴾ هَذَا اللَّفْظ فِي الْعَرَبيَّة مجْرَاه مجْرى التَّعَجُّب، كَأَنَّهُ قَالَ: أَي شَيْء هُمْ؟ يُقَال فِي الْكَلَام: فلانٌ مَا فلانٌ، وَمَجْرَاهُ من اللَّه ﷿ فِي مُخَاطبَة الْعباد مَجْرى مَا يُعَظمُ بِهِ الشَّأْن عندهُمْ، وَكَذَلِكَ هَذَا فِي قَوْله: ﴿مَا أَصْحَاب المشأمة﴾ أَي: أيّ شَيْء