"Then see how was the end of those who were warned," meaning: their end was that Allah destroyed them, then consigned them to the Fire.
Tafsir of Surah as-Saffat, verses 75 to 94.
﴿فَانْظُرْ كَيْفَ كَانَ عَاقِبَةُ الْمُنْذَرِينَ﴾ أَي: كَانَ عاقبتهم أَن دمر الله عَلَيْهِم ثمَّ صيرهم إِلَى النَّار.
تَفْسِير سُورَة الصافات الْآيَات من آيَة ٧٥ إِلَى آيَة ٩٤.
