Source: Fatāwā Amunpuri by Shaykh Ghulam Mustafa Zaheer Amunpuri
If a trustworthy narrator (thiqah rāwī) is alone in narrating a report, what is the ruling regarding that narration?
If a trustworthy narrator is the only one reporting a narration or specific wording, then according to the principles of the Hadith scholars, that narration is considered ṣaḥīḥ, provided that no expert Imam of ʿilal al-ḥadīth (hidden defects) has critiqued it. This is because the addition or singularity (tafarrud) of a trustworthy narrator is accepted.
✔ Imam al-Ḥākim رحمه الله (405 AH):
“If a trustworthy narrator is alone in narrating a ḥadīth, then according to the methodology of the Hadith scholars, it is ṣaḥīḥ.”
(المستدرك: 3/129)
Conclusion:
The solitary narration of a trustworthy narrator is regarded as authentic, as long as no authoritative scholar of Hadith criticism has identified a defect in it. The principle is that the addition or uniqueness of a trustworthy narrator is accepted.
◈ Question:
If a trustworthy narrator (thiqah rāwī) is alone in narrating a report, what is the ruling regarding that narration?
◈ Answer:
If a trustworthy narrator is the only one reporting a narration or specific wording, then according to the principles of the Hadith scholars, that narration is considered ṣaḥīḥ, provided that no expert Imam of ʿilal al-ḥadīth (hidden defects) has critiqued it. This is because the addition or singularity (tafarrud) of a trustworthy narrator is accepted.
❀ Statement of the Scholars
✔ Imam al-Ḥākim رحمه الله (405 AH):
“If a trustworthy narrator is alone in narrating a ḥadīth, then according to the methodology of the Hadith scholars, it is ṣaḥīḥ.”
(المستدرك: 3/129)

The solitary narration of a trustworthy narrator is regarded as authentic, as long as no authoritative scholar of Hadith criticism has identified a defect in it. The principle is that the addition or uniqueness of a trustworthy narrator is accepted.