والذين آمنوا واتبعتهم ذريتهم بإيمان ألحقنا بهم ذريتهم وما ألتناهم من عملهم (52:21) بالانجليزي

(52:21) We shall unite the believers with those descendants of theirs who followed them in their faith, and shall not deny them any part of the reward for their good deeds. *15 Every person is pledged to what he did. *16

Tafseer Abu-al-A'la Maududi

Page 524 English Traditional

*15) This theme has already been mentioned in Surah Ar-Ra`d: 23 and AIMu'min: 8 above, but here a greater good news has been given. In the verse of Surah Ar-Ra'd only this much was said: "They will enter into them (Gardens) along with the righteous from among their forefathers, wives and descendants," and in Surah AI-Mu'min: "The angels ask forgiveness for the believers; they say Our Lord...(admit therein also) of their parents and wives and children who are righteous." Here, what has been said in addition is: If the children had been following in the footsteps of their forefathers in faith, they will be joined with them in Paradise even though they might not deserve, on the basis of their deeds, the same high rank which the elders would attain on the basis of their superior faith and deeds, and this joining will not be of the nature of occasional visits and meetings but they will be lodged permanently with them in Paradise as is borne out by the words: alhaqna bi-him. For the sake of further satisfaction it has been stated: "In order to be joined with their offspring the parents will not be lowered and reduced in rank, but in order to be joined with their elders the rank of the children will be enhanced and exalted".
Here, it should be borne in mind that this news has been given in respect of the children who on reaching maturity voluntarily decided to affirm faith and of their own free will followed in the footsteps of their righteous forefathers. As for those of the children of a believer, who might have died even before reaching maturity, there cannot be any question of belief or disbelief, obedience or disobedience, for they will be admitted to Paradise automatically and will be lodged along with their parents to be a comfort of the eyes for them.
*16) Here, the metaphor of rahn (pledge) is very meaningful. If a person takes a loan from somebody, and the creditor keeps some article belonging to the debtor as a pledge with himself as a guarantee for the payment of his right, the debtor cannot redeem his pledge unless he pays off the debts; and if he does not redeem his pledge within the fixed time limit, the pledged article stands forfeited. The nature of the affair between man and God has been compared here to this very situation. The provisions, powers, capabilities and authority that God has granted man in the world are a debt that the Master has given to His servant, and as a guarantee for this debt the self of man is a pledge with AIIah. If man by employing the provisions and the powers and authority in the right way earns the good by which the debt can be paid off, he will redeem the pledged thing, i.e. his own self, otherwise it will be forfeited. This thing has been said immediately after the preceding verse because even though the righteous believers may themselves be the people of a very high rank, their children cannot redeem their pledge unless they redeem their self by their own labor and effort. The earning of the forefathers cannot redeem the children. However, if the children are able to redeem themselves by virtue of their faith in some degree by following their righteous forefathers in their footsteps, it would then be Allah's grace and bounty that in Paradise He may exalt them from lower ranks to be joined with their parents in the higher ranks. The good done by the forefathers can benefit the children only so far, but if by their own deeds they deserve Hell, it is not possible that they may be admitted to Paradise for the sake of the forefathers. Another thing that can be deduced from this verse is that the less righteous children's being joined with their more righteous forefathers is not in reality the result of the lifework of the children but of their forefathers'. They by virtue of their deeds will deserve the grace that their children be joined with them in order to be a comfort of the eyes for them. That is why Allah will not lower their ranks to join them with their children but will exalt the children's ranks to be joined with them, so that the perfection of Allah's blessings on them is not marred by the distress that they may suffer on account of the remoteness of their children far away.