Tafsir of Al-Furqan 25:76

Al-Furqan: (76) Remaining therein forever; excellent it is...

It means that when the Almighty first promised the benefits, and secondly the glorification, He clarified that permanence is one of their characteristics, which is meant by His saying: {Remaining therein} (Khālidīna fīhā).

Also, purity/sincerity is one of their characteristics, which is meant by His saying: {excellent it is as a resting place and as an abode} (ḥusnat mustaqarran wa muqāman).

This is in contrast to His saying [regarding the disbelievers]: {evil it was as a resting place and as an abode} (sā’at mustaqarran wa muqāman). That is, how evil that [place] is, and how excellent this [place] is!

{Say: My Lord would not care for you were it not for your supplication; for you have denied, so it will be an inevitable consequence.} (Qul mā ya‘ba’u bikum Rabbī law lā du‘ā’ukum faqad kadhdhabtum fa-sawfa yakūnu lizāman.)