Al-Ahzaab 33:37

And [remember, O Prophet] when you were saying to the one[30] who was favored by Allah[31] and favored by you[32], “Keep your wife and fear Allah.” You were concealing in your heart what Allah was going to reveal[33], and you were fearing people[34], while it was more fitting that you should fear Allah[35]. When Zayd no longer had desire for her, We gave her to you in marriage, so that there would be no restraint for the believers in marrying the ex-wives of their adopted sons when they no longer have desire for them. And Allah’s decree is bound to be fulfilled.

[30] It refers to the Prophet's adopted son, Zayd ibn Hārithah, before the adoption was abolished.
[31] By guiding him to Islam.
[32] By emancipating him from bondage.
[33] i.e., the command of Allah to the Prophet (ﷺ) to marry Zaynab bint Jahsh after Zayd divorced her; in order to make clear to people that a man can marry a woman previously married to his adopted son.
[34] i.e., fear that people may say that he married the former wife of his adopted son.
[35] By making Allah’s command known to people.

And [remember, O Muḥammad], when you said to the one on whom Allāh bestowed favor and you bestowed favor,[1198] "Keep your wife and fear Allāh," while you concealed within yourself that which Allāh is to disclose.[1199] And you feared the people,[1200] while Allāh has more right that you fear Him.[1201] So when Zayd had no longer any need for her, We married her to you in order that there not be upon the believers any discomfort [i.e., guilt] concerning the wives of their claimed [i.e., adopted] sons when they no longer have need of them. And ever is the command [i.e., decree] of Allāh accomplished.

[1198] Referring to the Prophet's freed slave, Zayd bin Ḥārithah.
[1199] i.e., Allāh's command to the Prophet (ﷺ) to marry Zaynab after Zayd divorced her. This was to demonstrate that a man may marry a woman formerly married to his adopted son.
[1200] i.e., feared their saying that the Prophet (ﷺ) had married the (former) wife of his son (which is prohibited by Allāh in the case of a true, begotten son).
[1201] By making known His command.

37. And (remember) when you said to him (Zaid bin Hârithah رضي الله عنه - the freed-slave of the Prophet صلى الله عليه وسلم) on whom Allâh has bestowed Grace (by guiding him to Islâm) and you (O Muhammad صلى الله عليه وسلم too) have done favour (by manumitting him): "Keep your wife to yourself, and fear Allâh." But you did hide in yourself (i.e. what Allâh has already made known to you that He will give her to you in marriage) that which Allâh will make manifest, you did fear the people (i.e., their saying that Muhammad صلى الله عليه وسلم married the divorced wife of his manumitted slave) whereas Allâh had a better right that you should fear Him. So when Zaid had accomplished his desire from her (i.e. divorced her), We gave her to you in marriage, so that (in future) there may be no difficulty to the believers in respect of (the marriage of) the wives of their adopted sons when the latter have no desire to keep them (i.e. they have divorced them). And Allâh’s Command must be fulfilled.

And when thou saidst unto him on whom Allah hath conferred favour and thou hast conferred favour: Keep thy wife to thyself, and fear Allah. And thou didst hide in thy mind that which Allah was to bring to light, and thou didst fear mankind whereas Allah hath a better right that thou shouldst fear Him. So when Zeyd had performed that necessary formality (of divorce) from her, We gave her unto thee in marriage, so that (henceforth) there may be no sin for believers in respect of wives of their adopted sons, when the latter have performed the necessary formality (of release) from them. The commandment of Allah must be fulfilled.