Purity: Mixing Turbah with Camphor
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 579:
It is recommended to mix some turbah from the grave of His Eminence Sayyid al-Shuhadāʾ [Imam al-Ḥusayn] (ʿA) with the camphor. However, the camphor must not be applied to places on the body that would cause disrespect to that earth. Furthermore, the amount of turbah should not be so great that when mixed with the camphor, it can no longer be called ‘camphor’.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)