Usul al-Kafi
Book 5:
The Book of Belief and Disbelief

Chapter51
Truthfulness and trustworthiness

776. 1. Imam Jafar as-Sadiq (p): God has not appointed any prophet but with truthfulness and trustworthiness.(B5,C51,T1)

777. 2. Imam Jafar as-Sadiq (p): Don’t be led away only by the prayer and fasting of a person because sometimes he becomes so addicted to prayer and fasting that he becomes restless without them. The real test is truthfulness and trustworthiness.(B5,C51,T2)

778. 3. Imam Jafar as-Sadiq (p): Actions of those who are truthful are virtuous and pure.(B5,C51,T3)
779. 10. Imam Jafar as-Sadiq (p): Do not exhort people to virtue only with words, but also with your deeds so that they may see your virtue and truthfulness.(B5,C51,T10)

780. 11. Imam Jafar as-Sadiq (p): …One who is truthful, his actions are virtuous and pure.(B5,C51,T11)