"[For those who did good]" means they believed; "[the best reward]" is Paradise, "[and an increase]" is gazing upon the Face of Allah - may He be glorified and exalted.
﴿للَّذين أَحْسنُوا﴾ آمنُوا ﴿الْحسنى﴾ الْجنَّة ﴿وَزِيَادَة﴾ النَّظَرُ إِلَى وَجْهِ اللَّهِ ﷿.
