Ibn Shihab relates that among the Ansar who took part in the Pledge of Aqabah, and then from Banu Sa'idah bin Ka'b, is the name of Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him); he was a naqib (leader).
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5334