Lady Umm Mundhir bint Qais (may Allah be pleased with her) narrated: One day, the Messenger of Allah (peace and blessings be upon him) came to my house, and Sayyiduna Ali (may Allah be pleased with him) was with him. He had recovered from an illness and was therefore weak. There were bunches of half-ripe dates hanging in our house. The Messenger of Allah (peace and blessings be upon him) and Ali (may Allah be pleased with him) began to eat from them. Then the Messenger of Allah (peace and blessings be upon him) said to Sayyiduna Ali (may Allah be pleased with him): "Wait, you (have just recovered from illness and) are weak." So Ali (may Allah be pleased with him) stopped. She (Umm Mundhir, may Allah be pleased with her) said: I had cooked barley and beetroot, then I brought it to the Messenger of Allah (peace and blessings be upon him). The Messenger of Allah (peace and blessings be upon him) said: "Ali! Take from this (and eat), for it is more beneficial for you."
Hadith Referenceمسند اسحاق بن راهويه / كتاب المرضٰي و الطب / 677
Hadith Takhrij«سنن ابوداود ، كتاب الطب ، باب فى الحمية ، رقم : 3856 . سنن ترمذي ، ابواب الطب ، باب ماجاء فى الحمية ، رقم : 2037 . قال الشيخ الالباني : حسن . سنن ابن ماجه ، رقم : 3442 . مسند احمد : 363/6 .»