Hadith 7:110
al-Baihaqi's narration has:
"He did not give me permission (to fight), and did not consider me has having attained puberty." [Ibn Khuzaimah graded it Sahih (authentic)].
وَفِي رِوَايَةٍ لِلْبَيْهَقِيِّ: " فَلَمْ يُجِزْنِي, وَلَمْ يَرَنِي بَلَغْتُ " وَصَحَّحَهَا اِبْنُ خُزَيْمَةَ