Verily the one who enjoins good and prohibits wrong should possess three qualities: he should act upon that which he enjoins and abstain from that which he prohibits; he must be just with regards to what he enjoins and just with regards to what he prohibits; and he must be gentle in what he enjoins and gentle in what he prohibits.'
Imam Ja'far ibn Muhammad al-Sadiq [as]
al-Khisal, p. 109, no. 79