relying on them; when he had to fall back on his own memory, it deteriorated—this is (1) the mukhtalit (a narrator whose memory has become confused).
The ruling regarding such a narrator is that whatever he related before the confusion, if it can be clearly identified, is accepted; but if it (2) cannot be identified, judgment is suspended. The same applies to anyone about whom the matter is uncertain, and this (3) is known by considering the calibre of those who received reports from him.
[Strengthening a weak ḥadith through corroborating transmissions and the governing criteria]
Whenever a transmitter of poor memory is corroborated by a reliable narrator—one superior to him or at least his equal, not inferior—and likewise a mukhtalit whose narrations have (4) not been sorted out, a mastūr (of unknown reliability), a chain that is mursal, or a mudallas where the omitted link (5) is unknown, then their ḥadith is classified as ḥasan, not in itself but (6) by virtue of the combined weight (majmūʿ) of the corroborator (7) and the one corroborated. For each of them carries an equal (8) probability that his report is correct or (9) incorrect, the chances (10) being evenly balanced. When, therefore, a narration from reliable authorities arrives that agrees with one of them, that version is preferred (11).