Musnad Abu Ya'la al-Mawsili 114:2

Abu Khaythama narrated to us, Wahb ibn Jarir narrated to us, Hisham narrated to us, from Muhammad, from Anas, that Hilal ibn Umayyah accused his wife of adultery with Sharik ibn Sahma. The Messenger of Allah (peace be upon him) said: "Observe her; if she brings him forth white and straight-haired, then he belongs to Hilal ibn Umayyah. And if she brings him forth dark-eyed, curly-haired, and thin-legged, then he belongs to Sharik ibn Sahma." She then brought him forth dark-eyed, curly-haired, and thin-legged.