Hawzah News Agency – The commander of the faithful Imam Ali peace be upon him says:
الصَّديقُ الصَّدوقُ: مَن نَصَحَكَ في عَيبِكَ، وحَفِظَكَ في غَيبِكَ، وآثَرَكَ على نَفسِهِ.
‘A sincere friend is he who advises you with regard to your shortcomings, protects you in your absence, and prefers you over himself.’
Source: Ghurar al-Hikam, no. 1904