It was narrated from Ibn 'Abbas that:
Hilal bin Umayyah accused his wife in the presence of the Prophet (ﷺ) of (committing adultery) with Sharik bin Sahma'. The Prophet said: "Bring proof or you will feel the Hadd (punishment) on your back." Hilal bin Umayyah said: "By the One Who sent you with the truth, I am telling the truth, and Allah will send down revelation concerning my situation which will spare my back." Then the following was revealed: "And for those who accuse their wives, but have no witnesses except themselves, let the testimony of one of them be four testimonies (i.e., testifies four times) by Allah that he is one of those who speak the truth. And the fifth (testimony should be) the invoking of the curse of Allah on him if he be of those who tell a lie (against her). But it shall avert the punishment (of stoning to death) from her, it she bears witness four times by Allah, that he (her husband) is telling a lie. And the fifth (testimony) should be that the wrath of Allah be upon her if he (her husband) speaks the truth." The Prophet (ﷺ), turned and sent for them, and they came. Hilal bin Umayyah stood up and bore witness, and the Prophet (ﷺ) said: "Allah knows that one of you is lying. Will either of you repent?" Then she stood up and affirmed her innocence. On the fifth time, meaning that the wrath of Allah be upon her if he (her husband) speaks the truth, they said to her: "It will invoke the wrath of Allah." Ibn 'Abbas said: "She hesitated and backed up, until we thought that she was going to recant. Then she said: 'By Allah, I cannot dishonor my people for ever.' Then the Prophet (ﷺ) said: 'Wait and see. If she gives birth to a child with black eyes, fleshy buttocks and big calves, then he is the son of Sharik bin Sahma'.' And she gave birth to such a child. Then the Prophet (ﷺ) said: 'Had it not the matter been settled by the Book of Allah, I would have punished her severely.' "
English reference: Vol. 3, Book 10, Hadith 2067
Arabic reference: Book 10, Hadith 2145