Al-Aḥzāb: 36
"It is not for a believing man..."
The Messenger of Allah (ﷺ) proposed to Zaynab bint Jaḥsh—the daughter of his paternal aunt, Umaymah bint ʿAbd al-Muṭṭalib—on behalf of his freedman, Zayd ibn Ḥārithah. She refused, and her brother ʿAbd Allāh also refused. Then this verse was revealed. They said, "We are satisfied, O Messenger of Allah." So he married her to him and paid her dowry on his behalf: sixty dirhams, a headscarf, a mantle, a shirt, a waist-wrapper, fifty mudds of food, and thirty ṣāʿs of dates.
It is also said: This refers to Umm Kulthūm bint ʿUqbah ibn Abī Muʿayṭ, the first woman to migrate. She offered herself to the Prophet (ﷺ), and he said, "I have accepted," and married her to Zayd. She and her brothers were displeased, saying, "We intended the Messenger of Allah, but he married us to his slave."
The Meaning:
It is not valid for any man or woman among the believers, "when Allah and His Messenger have decided a matter"—meaning, when the Messenger of Allah has decreed something, for his decree is the decree of Allah—"to have a choice in their affair." Rather, it is their duty to make their own opinions subordinate to his, and their choices secondary to his.
If you ask: The pronoun should have been singular, as in the saying: "No man or woman came to me except that his affair was such-and-such."
I reply: Yes, but since both were under the negation, it encompasses every believer, male and female; thus, the pronoun refers to the meaning, not the wording. It has been recited as takūn (feminine) and yakūn (masculine).
"Al-khiyarah" (choice): That which one chooses.
Al-Aḥzāb: 37
"And [remember, O Muhammad,] when you said to the one on whom Allah bestowed favor and you bestowed favor: 'Keep your wife and fear Allah,' while you concealed within yourself that which Allah was to disclose. And you feared the people, while Allah has more right that you fear Him. So when Zayd had no longer any need for her, We married her to you, so that there will be no discomfort for the believers concerning the wives of their adopted sons when they no longer have need of them. And ever is the command of Allah accomplished."