It was transmitted from ʿAmmār ibn Hāriz that he said: „I went to ʿAbī ʿAbdallāh [Imām Jaʿfar ibn Muḥammad ibn ʿAlī al-Ṣādiq] (peace be upon him) on the 18th of Ḏū al-Ḥijja and found him fasting. He said to me: „This is a great day. Allāh has glorified the sanctity of this day for the true believers and perfected the religion for them and completed the benefits for them and renewed the vow He had taken from them.“ [Miṣbāḥ al-mutahajjid , by al-Ṭūsī, page 737]

عَنْ عَمَّارِ بْنِ حَرِيزٍ قَالَ: دَخَلْتُ عَلَى أَبِي عَبْدِ اللَّهِ فِي يَوْمِ الثَّامِنَ عَشَرَ مِنْ ذِي الْحِجَّةِ فَوَجَدْتُهُ صَائِمًا فَقَالَ لِي: هَذَا يَوْمٌ عَظِيمٌ عَظَمَ اللَّهُ حُرْمَتَهُ عَلَى الْمُؤْمِنِينَ وَ أَكْمَلَ لَهُمْ فِيهِ الدِّيْنَ وَ تَمَّمَ عَلَيْهِمُ النِّعْمَةَ وَ جَدَّدَ لَهُمْ مَا أَخَذَ عَلَيْهِمْ مِنَ الْعَهْدِ وَالْمِيثَاقِ

Imām ʿAlī (peace be upon him) said: „Verily, this is a highly recognized day when redemption was brought, and the rank was raised, and the proofs (of Allāh) were made manifest. This is the day when from a pure rank, the words were pronounced clearly and directly, and this is the day of the completion of religion and when the promise and the oath of allegiance were taken. (…)“ [Biḥār al-Anwār, by al-Maǧlisī, Volume 97, Page 116]

قَالَ عَلِيَّ إِنَّ هَذَا يَوْمٌ عَظِيمُ الشَّأْنِ فِيهِ وُقِعَ الْفَرَجُ، وَرُفِعَتْ الدَّرَجُ وَ وُضِحَتِ الْحُجَجُ وَهُوَ يَوْمُ الْإِبْصَاحِ وَالإِفْصَاحِ مِنَ … الْمَقَامِ الصِّرَاحِ، وَيَومُ كَمَالُ الدِّينِ وَيَوْمُ الْعَهْدِ الْمَعْهُودِ