"And if they ask to be excused," meaning: if they ask Allah to bring them out of the Fire and return them to the world so that they may believe, "then they are not of those who are excused," meaning: they will not be excused.
Interpretation of Surah Fussilat from verse 25 to verse 29.
﴿وَإِن يستعتبوا﴾ أَي: يطلبوا إِلَى اللَّه أَن يخرجهم من النَّار؛ فيردّهم إِلَى الدُّنْيَا ليؤمنوا ﴿فَمَا هُمْ مِنَ المعتبين﴾ أَي: لَا يستعتبون.
تَفْسِير سُورَة فصلت من الْآيَة ٢٥ إِلَى آيَة ٢٩.