Musnad Ahmad 26:726

Muhammad ibn Ja’far narrated to us, he said: A man marries and does not specify a dowry for her, then he dies. Sa’id narrated to us, from Qatadah, from Khallas and Abu Hassan al-A’raj, from Abdullah ibn Utbah ibn Mas’ud, that he said: They differed before Ibn Mas’ud regarding that for a month or close to that, and they said: "You must say something regarding it." He said: "I judge for her the like of the dowry of a woman from her peers, neither less nor excessive, and she has the inheritance, and she must observe the waiting period (iddah)." "If it is correct, then it is from Allah the Almighty and Majestic, and if it is a mistake, then it is from me and from Satan, and Allah the Almighty and Majestic and His Messenger are free from it." Then a group from Ashja’ stood up, among them were al-Jarrah and Abu Sinan, and they said: "We bear witness that the Messenger of Allah (peace and blessings of Allah be upon him) judged regarding a woman from among us called Birwa’ bint Washiq with the like of what you have judged." Ibn Mas’ud rejoiced greatly at that, when his opinion coincided with the judgment of the Messenger of Allah (peace and blessings of Allah be upon him).