Nahj al-Balāgha

Hadith 1780
certaintytruthfulness
١٨٤. وَقَالَ (عليه ‏السلام): مَا شَكَكْتُ فِي الْحَقِّ مُذْ أُرِيتُهُ.
184. Amir al-mu'minin, peace be upon him, said: I have never entertained doubt about right since I was shown it.
Source: al-Sharīf al-Raḍī