—namely, the hidden variety—and this is the preferred view, endorsed by ʿAlī ibn al-Madīnī, al-Bukhārī, and other hadith critics (1).

[The Unrestricted Use of mushāfaha and mukātaba]
They also used (2) the term mushāfaha (face-to-face transmission) for an ijāza that is conferred verbally, by way of figurative extension (3). In the same manner (4) they applied the word mukātaba to an ijāza (5) granted through writing. This usage is found in the language of many later scholars, unlike the earlier authorities, for the latter would only (6) apply it to a case in which the shaykh had actually written (7) the hadith out for the student—whether or not he authorized him to transmit it—and not when (8) he merely wrote to him granting ijāza alone (9).

[munāwala and the Conditions for Accepting It]
They stipulated, for a narration transmitted by munāwala (10) to be sound, that it be accompanied (11) by explicit permission to transmit. When this condition is met, it becomes the highest form of ijāza because of the precision and personal identification it involves.