COMMENTARY on 39:49
A. Yusuf Ali:

Translation:
Now, when trouble touches man, he cries to Us: 4318 But when We bestow a favour upon him 4319 as from Ourselves, he says, "This has been given to me because of a certain knowledge (I have)!" 4320 No, but this is but a trial, but most of them understand not!
Commentary:

4318  Cf. 30:33 and n. 3545.

4319  Cf. 39:8 above.

4320  Cf. 28:78, and n. 3408. Prosperity may be a trial as much as adversity.

 

Muhammad Asad:

Translation:
NOW [thus it is:] when affliction befalls man, he cries out unto Us for help; but when We bestow upon him a boon by Our grace, he says [to himself], “I have been given [all] this by virtue of [my own] wisdom!” 55 Nay, this [bestowal of grace] is a trial: but most of them understand it not!
Commentary:
55  Lit., "knowledge" - i.e., "my prosperity is due to my own ability and shrewdness": see the first sentence of 28:78 and the corresponding note. But whereas there this "saying" or thought is attributed to the legendary Qarun, in the present instance - which is by far the earlier in the chronology of Quranic revelation - it is said to be characteristic of man as such (see, e.g., 7:189-190, where this tendency is referred to in connection with the experience of parenthood).