It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that a man came to the Prophet (peace and blessings be upon him) and said: I have had no relations with my wife since the 'ifar of the palm trees (and their 'ifar was that they would be pollinated, and then after the pollination they would not be watered for forty days); then I found a man with my wife. (And the woman's husband was of yellowish complexion, thin-bodied and straight-haired, while the man to whom she was attributed was thick-limbed, blackish, curly-haired and large-buttocked.) So the Messenger of Allah (peace and blessings be upon him) said: "O Allah, make the truth clear; O Allah, make the truth clear." Then he ((peace and blessings be upon him)) had the two of them undergo li'an, and the woman gave birth to a child who resembled the man to whom she had been attributed.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10668