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 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.