Sunan Abu Dawud #4317 · Battles (Kitab Al-Malahim)

Sunan Abu DawudShu’bah said in his version
Sunan Abu Dawud · Book 39 · Battles (Kitab Al-Malahim)
Sunan Abu Dawud · كتاب 39 · كتاب الملاحم
“the letters k, f, r” (are on his forehead)
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، عَنْ مُحَمَّدِ بْنِ جَعْفَرٍ، عَنْ شُعْبَةَ، ك ف ر ‏.‏
Reference : Sunan Abu Dawud 4317In-book reference : Book 39, Hadith 27