Majma al-Zawaid — Hadith 3820

It is reported about Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) that he said: "O Messenger of Allah! What is the recompense for fever?" The Prophet (peace and blessings be upon him) said: "It keeps the good deeds of the one afflicted with it flowing, as long as his foot trembles or his vein throbs against him." Sayyiduna Ubayy said: "O Allah! I ask You for a fever that does not prevent me from going out in Your path (for jihad), or going out to Your House, or to the mosque of Your Prophet." The narrator says: Thereafter he never reached the evening except that he had a fever.
Al-Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat through Muhammad bin Mu'adh bin Ubayy bin Ka'b from his father. Both of these narrators are majhul (unknown), as Yahya bin Ma'in stated.
(Allamah al-Haythami says:) I say: Ibn Hibban has mentioned both of them in the book al-Thiqat.
(Allamah al-Haythami says:) I say: Two chapters before this, a hadith narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) has already passed (in which the incident of Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) is mentioned).