Definition of Al-Mutamathhilayn:
Two identical letters: sharing the same articulation point and attributes — i.e., the same letter repeated, the first with sukoon and the second voweled.
Ruling:
The first is merged into the second obligatorily — they become one doubled letter.
Quranic examples:
— "Idhhab bi-kitabi" (28:28) — the sukoon baa in "idhhab" merges into the baa of "bi-kitabi": "idhhabbikitabi"
— "Qad dakhalu" (24:61) — sukoon daal of "qad" merges into daal of "dakhalu": "qaddakhalu"
— "Yudrikkkum" originally "yudrikakum" — sukoon kaf merges into voweled kaf
Al-Mutamathhilayn Al-Kabeer:
When both letters are voweled — this is the large mutamathhilayn, an optional idgham for some readers but not Hafs.
Difference between mutamathhilayn, mutaqaribayn, and mutajanisayn:
- Mutamathhilayn: same articulation and same attributes (بب / دد / قق)
- Mutajanisayn: same articulation but different attribute (طت / ذد / بم)
- Mutaqaribayn: close articulation or close attributes (رل / نل / قك)
Question: What is the difference between mutamathhilayn and mutajanisayn? Give an example of each.
Answer: Mutamathhilayn: same articulation and attributes (qad dakhalu — daal+daal). Mutajanisayn: same articulation with different attribute (qad tabayyana — daal+taa).