Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) narrates from Sayyidah Asma bint Umays (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) came to her one day while she was pounding shubrum (a purgative herb). He (peace and blessings be upon him) asked: "What do you do with it?" She said: We give it to so-and-so to drink (so that his bowels are cleared). He (peace and blessings be upon him) said: "It is a disease (that is, extremely harsh and harmful)." (The narrator said:) Then he (peace and blessings be upon him) came again, and she had senna (senna of Makkah) with her. He (peace and blessings be upon him) asked: "What do you do with this?" She said: So-and-so drinks it. He (peace and blessings be upon him) said: "If there were anything that could ward off death, or be of benefit against death, it would be senna." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.