It is narrated about Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) that he said: A man came to the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) asked: "When did you last have 'Umm Mildam'?" (The narrator says:) It is a heat that is felt between the skin and the flesh (perhaps fever is meant). He said: "This pain has never afflicted me." The Prophet (peace and blessings be upon him) said: "The likeness of the believer is like a tender plant (or fresh grass), which sometimes turns red and sometimes turns yellow."
Ahmad recorded it, and its chain contains a narrator who has not been named.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجنائز / 3746