"Or do they say, 'He has forged it?'"—meaning that Muhammad has fabricated the Quran. "Say, 'If I have forged it, then upon me is my crime, and I am innocent of what you commit'"—meaning, upon me is my own deed, and I am innocent of what you do.
Muhammad said: "Al-ijram" (the crime) is the act of committing a sin, and it is the verbal noun (masdar) of "ajramtu" (I committed a crime).
﴿أم يَقُولُونَ افتراه﴾ إِنَّ مُحَمَّدًا افْتَرَى الْقُرْآنَ ﴿قُلْ إِنِ افْتَرَيْتُهُ فَعَلَيَّ إِجْرَامِي وَأَنَا بريءٌ مِمَّا تجرمون﴾ يَقُولُ: فَعَلَيَّ عَمَلِي، وَأَنَا بريءٌ مِمَّا تَعْمَلُونَ.
قَالَ محمدٌ: الإِجْرَامُ: الإِقْدَامُ عَلَى الذَّنْبِ؛ وَهُوَ مَصْدَرُ أجرمت.