We set out with the Messenger of Allah ﷺ to Hunayn, and he then mentioned the meaning of Muamar's hadith, though Muamar's narration was more complete.
حدثنا إسحاق بن سليمان حدثنا مالك بن أنس عن الزهري عن سنان بن أبي سنان الدؤلي
خرجنا مع رسول الله ﷺ إلى حنين فذكر معنى حديث معمر ومعمر أتم حديثا
No references are available.
Its isnad is sahih. Ishaq bin Sulayman is Razi, and he is trustworthy, his hadith appearing in Muslim. Ahmad is referring to the hadith of Mamar mentioned earlier at 21797.