Abu Ishaq says: I saw a man who asked Aswad bin Yazid, who used to teach the Qur'an in the mosque, and said: How should we recite this verse: {فَہَلْمِنْمُدَّکِرٍ} Is it with "dh" or "d"? He replied: No, it is with "d". I heard Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) say, he said: I heard the Messenger of Allah (peace and blessings be upon him) recite {مُدَّکِرٍ} with "d".
Hadith Referenceالفتح الربانی / تفسير من سورة محمد إلى سورة التحريم / 8772
Hadith Gradingمحدثین:صحیح
Hadith Takhrij«أخرجه البخاري: 4871، ومسلم: 823، (انظر مسند أحمد ترقيم الرسالة: 4401 ترقیم بيت الأفكار الدولية: 4401»
Brief Explanation
Benefits: … The word مُدَّکِر was originally مُذْتَکِر. Its pronunciation was heavy on the tongues, so first the letter "ت" was changed to "د", then "ذ" was changed to "د" and merged (idgham) accordingly.