Majma al-Zawaid — Hadith 9571

Sayyiduna Abu Humayd al-Sa'idi (may Allah be pleased with him) narrates: On the occasion of the Battle of Uhud the Prophet (peace and blessings be upon him) set out, until, when he had passed Thaniyyat al-Wada', there was a military detachment there. He asked: "Who are these people?" The people said: "This is Abdullah bin Ubayy with six hundred of his allies (mawali) from the Jews of Banu Qaynuqa'." The Prophet (peace and blessings be upon him) asked: "Have these people accepted Islam?" The people said: "No, O Messenger of Allah!" The Prophet (peace and blessings be upon him) said: "Tell them to go back, for we will not seek help from polytheists against polytheists."
Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat. Its chain contains Sa'd bin al-Mundhir bin Abi Humayd, whom Ibn Hibban mentioned in Kitab al-Thiqat, saying: "This is Sa'd bin Abi Humayd," so he attributed him to his grandfather. The rest of its narrators are thiqat (trustworthy).