Nahj al-Balāgha
Hadith 1126أَدْحَضُ مَسْؤُول حُجَّةً، وَأَقْطَعُ مُغْتَرٍّ مَعْذِرَةً، لَقَدْ أَبْرَحَ جَهَالَةً بِنَفْسِهِ.
The addressee (in this verse) is devoid of argument and his excuse is most deceptive. He is detaining himself in ignorance.