Al-Ahzab 33:37 واذ تقول للذي انعم الله عليه وانعمت عليه امسك عليك زوجك واتق الله وتخفي في نفسك ما الله مبديه وتخشى الناس والله احق ان تخشاه فلما قضى زيد منها وطرا زوجناكها لكي لا يكون على المومنين حرج في ازواج ادعيايهم اذا قضوا منهن وطرا وكان امر الله مفعولا ٣٧

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.