Sayyiduna Abbas bin Sahl bin Sa'd (may Allah be pleased with him) narrates: I heard Sayyiduna Abu Usayd (may Allah be pleased with him) say: "I took part in twenty military expeditions with the Prophet (peace and blessings be upon him), one expedition after another."
Al-Bazzar recorded it; its chain contains al-Waqidi, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15962