Musnad Ahmad 26:850

Abu Kamil narrated to us, Zuhayr narrated to us, Abu Ishaq narrated to us, he said: I saw a man ask al-Aswad ibn Yazid, while he was teaching the Quran in the mosque, and he said: "How do you recite this word {فهل من مدكر} [Al-Qamar: 15], with a dhal (ذ) or a dal (د)?" He said: "No, rather a dal (د)." Then he said: "I heard Abdullah ibn Mas'ud say: I heard the Messenger of Allah, peace and blessings of Allah be upon him, recite it: {مدكر} [Al-Qamar: 15], with a dal (د)."