COMMENTARY on 24:21
A. Yusuf Ali:

Translation:
O you who believe! follow not Satan´s footsteps: if any will follow the footsteps of Satan, he will (but) command what is shameful and wrong: and were it not for the grace and mercy of Allah on you, not one of you would 2972 ever have been pure: but Allah do purify whom He pleases: 2973 and Allah is One Who hears and knows (all things).
Commentary:

2972  See last note.

2973  Spotless purity in thought, word, and deed, includes the disposition to put the best construction on the motives of others, so that we ascribe no evil motive to the seeming indiscretions of virtuous people. Such a high standard can only come by the grace of Allah, Who hears all prayers and knows all the temptations to which human nature is subject. His Will and Plan make both for spiritual protection and spiritual peace, and we must place ourselves trustingly in His hands.

 

Muhammad Asad:

Translation:
O You who have attained to faith! Follow not Satan’s footsteps: for he who follows Satan’s foot­steps [will find that], behold, he enjoins but deeds of abomination and all that runs counter to reason. 24 And were it not for God’s favour upon you and His grace, not one of you would ever have remained pure. For [thus it is:] God who causes whomever He wills to grow in purity: for God is all-hearing, all-­knowing.
Commentary:
24  In this context, the term al-munkar has apparently the same meaning as in 16:90 (explained in the corresponding note 109) since, as the sequence shows, it clearly relates to the unreasonable self-righteousness of so many people who "follow Satan’s footsteps" by imputing moral failings to others and forgetting that it is only due to Gods grace that man, in his inborn weakness, can ever remain pure.