COMMENTARY on 29:3
A. Yusuf Ali:

Translation:
We did test those before them, and Allah will certainly know 3424 those who are true from those who are false.
Commentary:

3424  The word "know" is used here more in the sense of testing than of acquiring knowledge. Allah is All-Knowing: He needs no test to increase His own knowledge, but the test is to burn out the dross within ourselves, as explained in the last note.

 

Muhammad Asad:

Translation:
Yea, indeed, We did test those who lived before them; and so, [too, shall be tested the people now living: and] most certainly will God mark out those who prove themselves true, and most certainly will He mark out those who are lying. 2
Commentary:
2  I.e., to others and/or to themselves (see note 7).