Taḥammul is how hadith material is acquired from a teacher or an authorized source; adāʾ is its subsequent transmission. How a narrator received something and how he later expressed that reception are separate questions.
Eight familiar modes of acquisition are:
1. Direct hearing from the teacher
2. Reading to the teacher (ʿarḍ)
3. Authorization (ijāzah)
4. Handing over material (munāwalah)
5. Written communication (mukātabah)
6. Informing a student (iʿlām)
7. Bequeathing a text (waṣiyyah)
8. Finding an existing document (wijādah)
These modes are not of identical strength and do not justify identical delivery formulas. Hearing means hearing a teacher’s wording; authorization grants permission but is not itself direct hearing. “Ḥaddathanī” must not be treated as interchangeable with “ajāzanī.”