Mishkat al-Masabih 4520
Aba Huraira told of hearing God’s messenger say:
“Nigella seed is a remedy for every disease but sam .” 
Ibn Shihab said sant is death and the nigella seed is shuniz .* 

(Bukhari and Muslim.)
* Taj al-’arus says this is a Persian word which came to be used by Arabs. It indicates a seed of a species of nigella.
وَعَن أَبِي هُرَيْرَةَ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «فِي الْحَبَّةِ السَّوْدَاءِ شِفَاءٌ مِنْ كُلِّ دَاءٍ إِلَّا السَّامَ» . قَالَ ابْنُ شِهَابٍ: السَّامُ: الْمَوْتُ وَالْحَبَّةُ السَّوْدَاءُ: الشُّونِيزُ