Al-Awza’i reported: Umar, may Allah be pleased with him, said, “O people, we do not find any excuse after the Sunnah for anyone to be in misguidance, embarking upon it and considering it guidance, nor to be in guidance, embarking upon it and considering it misguidance. The matters have been explained, the proof has been established, and the excuses have ended.”
Source: Tārīkh al-Madīnah li-Ibn Shabbah 3/800
عَنِ الْأَوْزَاعِيِّ عَنِ عُمَر رَضِيَ اللَّهُ عَنْهُ قَالَ أَيُّهَا النَّاسُ لَا نَجِدَنَّ أَحَدًا بَعْدَ السُّنَّةِ فِي ضَلَالَةٍ رَكِبَهَا حَسِبَهَا هُدًى وَلَا فِي هُدًى رَكِبَهُ حَسِبَهُ ضَلَالَةً قَدْ بَلَغَتِ الْأُمُورُ وَثَبَتَتِ الْحُجَّةُ وَانْقَطَعَ الْعُذْرُ
3/800 تاريخ المدينة لابن شبة