34. Surah Saba
The Quranic Text & Ali’s Version:
وَمَا كَانَ لَهُ عَلَيْهِم مِّن سُلْطَانٍ...
34:21 But he had no authority over them --
... إِلَّا لِنَعْلَمَ مَن يُؤْمِنُ بِالْآخِرَةِ مِمَّنْ هُوَ مِنْهَا فِي شَكٍّ...
except that We might test the man who believes in the Hereafter from him who is in doubt concerning it:
C3821. Might test. - the word in the original is might know.
It is not that Allah does not know all. Why does He want to test?
It is in order to help us subjectively, to train our will, to put us definitely the question, "Will you obey Allah or other than Allah?"
Cf. n. 467 to 3:154.
... وَرَبُّكَ عَلَى كُلِّ شَيْءٍ حَفِيظٌ ﴿٢١﴾
[wa rabbuka wala kulli shaiin hafiz]
and thy Lord doth watch over all things.