COMMENTARY on 39:55
A. Yusuf Ali:

Translation:
"And follow the Best 4326 of (the courses) revealed to you from your Lord, before the Penalty comes on you - of a sudden while you perceive not!-
Commentary:

4326  Cf. 39:18, and n. 4269. Allah's Command meets the weakness of His weakest servants, and only asks that His servants should surrender their selfish will to Allah's Will. In divine compassion, therefore, we are allowed to do just what we can, even though our standard should fall short of the highest standard, and Allah's Grace will come to our assistance. But we must do so in this life—and at once, as soon as the Word penetrates our mind or understanding. We must not delay a moment, for the Judgement may come at any time, suddenly, before we even perceive where we are.