COMMENTARY on 4:21
Mustafa Khattab:

Translation:
And how could you take it back after having enjoyed each other intimately and she has taken from you a firm commitment?8 
Commentary:
8   i.e., the promise to live with her in kindness or divorce her with dignity.

 

Muhammad Asad:

Translation:
And how could you take it away after you have given yourselves to one another, and she has 23 received a most solemn pledge from you?
Commentary:
23  Lit., "they have" - the reference being to all married women.