Surah Al-Kahf 18:88

وَأَمَّا مَنْ ءَامَنَ وَعَمِلَ صَـٰلِحًا فَلَهُۥ جَزَآءً ٱلْحُسْنَىٰ ۖ وَسَنَقُولُ لَهُۥ مِنْ أَمْرِنَا يُسْرًا

But as for one who believes and does righteousness, he will have a reward of the best [i.e., Paradise], and we [i.e., Dhul-Qarnayn] will speak to him from our command with ease."

Translation: Saheeh International

Tafsir

But as for him who believes and acts righteously he shall have the fairest reward namely Paradise the annexation construction jazā’u l-husnā ‘the fairest reward’ is explicative; a variant reading has jazā’an al-husnā ‘he shall have as a requital that which is fairest’; …

Excerpt from Tafsir al-Jalalayn, commentary on 18:88, via Quran.com. The reader has the full commentary and 9 more tafsirs.