"They look with a veiled gaze," meaning they steal glances. "Those who have lost their souls and their families on the Day of Resurrection," they lost their souls by failing to secure their salvation, so they ended up in the Fire, and they lost their families from among the Houris (maidens of Paradise), as we have already explained in Surah Az-Zumar.
﴿ينظرُونَ من طرف خَفِي﴾ أَي: يسارقون النّظر ﴿الَّذِينَ خَسِرُوا أنفسهم وأهليهم يَوْم الْقِيَامَة﴾ خسروا أنفسهم أَن يغنموها؛ فصاروا فِي النَّار , وخسروا أَهْليهمْ من الْحور الْعين , وَقد فسرناه فِي سُورَة الزمر
