Al-Kāfi - Volume 1 > Chapter on the Need for the Existence of a Divine Authority in the World and the Seriousness of this Matter
Hadith #3

3ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ وَمُحَمَّدُ بْنُ إِسْمَاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ جَمِيعاً عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ جَمِيلِ بْنِ دَرَّاجٍ قَالَ سَمِعْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلام) يَقُولُ إِذَا بَلَغَتِ النَّفْسُ هَاهُنَا وَأَشَارَ بِيَدِهِ إِلَى حَلْقِهِ لَمْ يَكُنْ لِلْعَالِمِ تَوْبَةٌ ثُمَّ قَرَأَ إِنَّمَا التَّوْبَةُ عَلَى الله لِلَّذِينَ يَعْمَلُونَ السُّوءَ بِجَهالَةٍ.

3. Ali ibn Ibrahim has narrated from his father and Muhammad ibn ’Isma‘il from al-Fadl ibn Shadhan, both from ibn abu ‘Umayr from Jamil ibn Darraj who has said the following. “(Imam) abu ‘Abdallah (a.s.) has said, “When the soul reaches here, pointing to his throat, there will be no chance for learned persons to repent. He recited this verse; “God will only accept the repentance of those who commit evil in ignorance, if they repent immediately. God is All-knowing and All-wise (4:17)”