COMMENTARY on 4:66
Mustafa Khattab:

Translation:
If We had commanded them to sacrifice themselves or abandon their homes, none would have obeyed except for a few. Had they done what they were advised to do,23 it would have certainly been far better for them and more reassuring,
Commentary:
23   i.e., obeying Allah and His Messenger.

 

A. Yusuf Ali:

Translation:
If We had ordered them to sacrifice their lives or to leave their homes, very few of them would have done it: 584 But if they had done what they were (actually) told, it would have been best for them, and would have gone farthest to strengthen their (faith);
Commentary:

584  The highest in faith willingly sacrifice their lives, their homes, and all that they hold dearest, in the cause of Allah. Those whose faith is not so strong are expected at least to do what a loyal member of any society does, submit his doubts and disputes to the head of the society and cheerfully accept his decision and submit to it. The contrast is between the hypocrites who will not even do this, and the really devoted men and women who would voluntarily sacrifice their lives.

 

Muhammad Asad:

Translation:
Yet if We were to ordain for them, 85 "Lay down your lives," or, "Forsake your homelands," only a very few of them would do it 86 - although, if they did what they are admonished to do, it would indeed be for their own good and apt to strengthen them greatly [in faith],
Commentary:
85  I.e., by means of the God-inspired commands issued by the Prophet (see preceding note).
86  Lit., "they would not do it, save for a few of them": the pronoun obviously relates to the half-hearted, who are not prepared to undergo the sacrifices which their faith demands of them. The reference to laying down one's life in the defence of faith and freedom and, if necessary, abandoning one's homeland, introduces, as it were, the long passage beginning with verse 71, which deals with fighting in God's cause.