Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) seated me behind him and seated Qutham in front of him. (Allamah al-Haythami says:) I say: The hadith about seating Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) behind him is mentioned in the Sahih.
Ahmad recorded it.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجهاد / 9374