Is it permissible to cite a less authentic hadith to identify an ambiguous narrator in an authentic hadith, by saying that the ambiguous narrator in the authentic chain of transmission is the Companion Jabir, citing as evidence the good chain of transmission in which Jabir's name was mentioned?

This issue falls under the conflict between wasl (connected transmission) and irsal (disconnected transmission) in hadith, and there is no fixed rule for it. Rather, one refers to the contextual clues surrounding each hadith. Al-Hafiz Ibn Hajar and others have stated that the early Imams did not rule with a universal judgment on this matter, but rather their work revolved around prioritizing for each hadith. An example of this is the hadith reported through two chains from Al-Zuhri; one of them is ambiguous concerning the Tabi'i, while the other explicitly names the Companion Jabir (may Allah be pleased with him). Al-Hafiz Ibn Hajar pointed out this difference in "Fath al-Bari." Al-Harith ibn Abi Usama narrated it from Al-Zuhri ambiguously, while Ibrahim ibn Hamza al-Zubairi narrated it from Ibrahim ibn Sa'd, explicitly mentioning Jabir (may Allah be pleased with him). Although Ibrahim ibn Hamza al-Zubairi is trustworthy, it appears that the mention of Jabir is a delusion, because Yunus ibn Yazid and Ma'mar ibn Rashid, who are more reliable and closer to Al-Zuhri than Ibrahim ibn Sa'd, narrated it ambiguously. This indicates that the preponderant view is the ambiguity of the Companion, and that the explicit mention of Jabir might be a delusion from Ibrahim ibn Sa'd.