[2:201] And there are others who say, 'Our Lord, give to us in this world good, and good in the Hereafter, and guard us against the chastisement of the Fire'.
He means in [this verse] good (ḥasana), the existence of which is consistent with all good things. The good by which all good things are obtained in this world is the protection of faith for them in the end. Surely whoever leaves this world as a believer will not remain in the Fire and the passing of this [world] will be of little consequence. The good which is consistent with the good things of the Hereafter is forgiveness, for when He forgives, there is nothing but every good after it.
It is said the good in this world is aversion to it and the good in the Hereafter is protection from dwelling in [the Fire]. The guarding is from the Fire and the fires of separation (furqa) since the [letter] lām in His saying al-nār is a generic lām, so they seeking refuge applies to both the fires of burning (nīrān al-ḥurqa) and the fires of separation (nīrān al-furqa).
It is said the good in this world is the witnessing by the innermost selves (bi'l-asrār) and in the Hereafter the vision by the physical eyes (bi'l-abṣār).
It is said the good of this world is that He annihilates you from yourself, while the good of the Hereafter is that He returns you to yourself.
It is said the good of this world is the success granted [by God] in service (tawfīq al-khidma) and the good of the Hereafter is the actualization of communion (taḥqīq al-wuṣla).