Musannaf Ibn Abi Shayba 24:151

Muhammad ibn al-Hasan al-Asadi narrated to us, he said: Sharik narrated to us, from Abu al-Jahhaf, from Abd al-Rahman ibn Abza, from Ali, he said: "Indeed, the fever is like the sting of a scorpion. So when that happens, then attach yourselves to your paternal aunt, the date palm," meaning the black [dates].