Walaqad fatanna allatheena min qablihim falayaAAlamanna Allahu allatheena sadaqoo walayaAAlamanna alkathibeen (surah Ankabut: 3)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(29:3) for We indeed tested those who went before them? *2 Allah will most certainly ascertain *3 those who spoke the truth and those who lied.

Wa laqad fatannal lazeena min qablihim fala ya`lamannal laahul lazeena sadaqoo wa la ya`lamannal kaazibeen

*2) That is, "This is not a new thing which you alone may be experiencing. The same has been happening before also. Whoever made a claim to the Faith was made to pass through trials and tribulations. And when the others were not given anything without the trial, you are in no way any special people that you should be favoured and rewarded merely on verbal profession of the Faith."
*3) Literally, "It is necessary that Allah should find out." A question may be asked: "When Allah already knows the truth of the truthful and the untruth of the liar, why should He put the people to the test for the sake of these?" The answer is: Until a person has manifested his potential and capability to do a thing in practical terms, justice requires that he neither deserves any rewards nor any punishment. One man, for example, is capable of being trustworthy and another man of being un-trustworthy. Unless both are tried and one manifests trustworthiness and the other the lack of it practically, it will not be justice on the part of Allah that He should reward one for trustworthiness and punish the other for the lack of it only on the basis of His knowledge of the unseen. Therefore the knowledge Allah already possesses about the capabilities of the people and about their conduct in the future is not enough to satisfy the requirements of justice until the people have manifested their potentialities in practical ways. Justice with AIlah is not based on the knowledge that a person possesses a tendancy to steal and will commit a theft, but on the knowledge that he has actually committed a theft. Likewise, Allah does not bestow favours and rewards on the basis of the knowledge that a person has the potential and capability to become a great believer and fighter in His way, but on the basis of the knowledge that the person concerned has practically proved by deed and action that he is a sincere believer and a brave fighter in His way. That is why we have translated the words of the verse as: "Allah has to see..."