COMMENTARY on 47:31
A. Yusuf Ali:

Translation:
And We shall try you 4855 until We test those among you who strive their utmost and persevere in patience; and We shall try your reported (mettle). 4856
Commentary:

4855  Cf. 34:21, and n. 3821. The test and trial is for our own psychological development, to help in the exercise of such choice as has been given to us in our free will. Cf. also 3:154, and n. 467.

4856  Akhbar. the things reported of you; reputation for courage and constancy, which has to be brought to the test of facts and experience. In an epigram of Tacitus we are told of a Roman Emperor that he would have been considered in every way to have been worthy of being a ruler if only he had never ruled! So in life people may think us courageous, true, noble, and self-sacrificing; and we may consider ourselves as possessing all such virtues; but it is actual experience that will bring them to the test.

 

Muhammad Asad:

Translation:
and most certainly We shall try you all, so that We might mark out 37 those of you who strive hard [in Our cause] and are patient in adversity: for We shall put to a test [the truth of] all your assertions. 38
Commentary:
37  Cf. 3:140, where the verb a1ama has been rendered in the same way.
38  Lit., "your announcements" - i.e., all assertions relating to belief. The "test" consists in one’s readiness to undergo any sacrifice - and, since most of this surah deals with the problem of a just war (jihad) in God’s cause - even the sacrifice of one’s life.