Nahj al-Balagha is the best-known collection of sermons, letters, and sayings attributed to the Commander of the Faithful Imam Ali ibn Abi Talib (as), the first Imam and the cousin and son-in-law of the Prophet Muhammad (saw).
Al-Sayyid al-Sharif al-Radi, a renowned Shia scholar in the tenth century AD, collected it, and it has been preserved since.
This is a beautiful publication translated by Sayyid Ali Raza.
