Al-Matalib al-'Aliyah 3025 — Seeking the chain of transmission

It is narrated from al-A'mash (may Allah have mercy on him) that he said: I requested of Ibrahim al-Nakha'i (may Allah have mercy on him): "When you narrate hadith to me, please also tell me their chains." He replied: "When I say to you 'Qala Abdullah' ('Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said'), then (know that) more than one narrator has narrated it to me from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him); but when I narrate naming a specific person, then it is narrated from that one person whom I have named."
Ishaq bin Rahwayh recorded this report (athar) in his Musnad, and its chain is sahih (authentic).