Imam Ali (AS) said, The friend has been named ṣadīq because he is truthful to you about your nature and faults, so have confidence in one who does this for he is your [true] friend.
الإمامُ عليٌّ (عَلَيهِ الّسَلامُ) : إنّما سُمِّيَ الصَّديقُ صديقاً لأنّه يَصْدُقُكَ في نَفْسِكَ و مَعائبِكَ فَمَنْ فَعَلَ ذلك فاستَنِمْ إليْهِ فإنَّهُ الصَّديقُ
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