عَنْ اَبِي بَصِيرٍ قَالَ دَخَلْتُ عَلَى اَبِي عَبْدِ اللهِؑ فَقُلْتُ لَهُ اِنَّ الشِّيعَةَ يَتَحَدَّثُونَ اَنَّ رَسُولَ اللهِ ﷺ عَلَّمَ عَلِيًّا بَابًا يُفْتَحُ مِنْهُ اَلْفُ بَابٍ فَقَالَ اَبُو عَبْدِ اللهِؑ يَا اَبَا مُحَمَّدٍ عَلَّمَ وَ اللهِ رَسُولُ اللهِ ﷺ عَلِيًّا اَلْفَ بَابٍ يُفْتَحُ لَهُ مِنْ كُلِّ بَابٍ اَلْفُ بَابٍ فَقُلْتُ لَهُ هَذَا وَ اللهِ الْعِلْمُ قَالَ اِنَّهُ لَعِلْمٌ وَ لَيْسَ بِذَاكَ
Abu Baseer (r.a.) informs, “I went to Imam Abu Abdillah (al-Sadeq a.s.) and said, ‘Verily, the Shiites narrate that the Messenger of Allah (peace be upon him and his holy progeny) taught Ali (peace be upon him) a door (of knowledge) from which a thousand doors opened (i.e. ten thousand doors).’ Imam (peace be upon him) corrected him, ‘O Aba Muhammad! Surely, the Messenger of Allah (peace be upon him and his holy progeny) taught Ali (peace be upon him) a thousand doors from each of which a thousand doors opened (i.e. a million doors).’ I said, ‘By Allah! This is the knowledge (all of it)!’
Again, Imam (peace be upon him) corrected, ‘Surely, it is knowledge (a part of it) but not in its entirety’.”
References:
1. Behaar al-Anwaar, vol. 26, p. 29, H. 33
2. Basaaer al-Darajaat, p. 303, H. 3, Chapter 16