The story of Zayd ibn Haritha and Zaynab

No believing men and women have any choice in a matter after God and His Apostle have decided it. Whoever disobeys God and His Apostle has clearly lost the way and gone astray.

When you said to him who had been favoured by God and was favoured by you: "Keep your wife to yourself and fear God," you were hiding something God was about to bring to light, for you had fear of men, though you should fear God more. And when Zaid was through with her, We gave her to you in marriage, so that it may not remain a sin for the faithful (to marry) the wives of their adopted sons when they are through with them. God's command is to be fulfilled.

There is no constraint on the Prophet in what God has decreed for him. This has been the way of God with (apostles) who have gone before you, and God's command is a determined act.

(For) those who convey the messages of God, and fear Him and no one else, God is sufficient to keep account.