Shu’bah said in his version:

“the letters k, f, r” (are on his forehead).

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، عَنْ مُحَمَّدِ بْنِ جَعْفَرٍ، عَنْ شُعْبَةَ، ك ف ر ‏.‏