Bulugh al-Maram, Book 12, Hadith 1400 (English)

Samurah (RAA) narrated that Allah's Messenger said: "Every boy is pawned against his 'Aqiqah, to be slaughtered on his behalf on the seventh day of his birth, his head is to be shaved, and he must be given a name." Related by the five Imams (Ahmad and the four Imams). At-Tirmidhi graded it as Sahih.

وَعَنْ سَمُرَةَ ‏- رضى الله عنه ‏- أَنَّ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-قَالَ: { "كُلُّ غُلَامٍ مُرْتَهَنٌ بِعَقِيقَتِهِ, تُذْبَحُ عَنْهُ يَوْمَ سَابِعِهِ, وَيُحْلَقُ, وَيُسَمَّى" } رَوَاهُ اَلْخَمْسَةُ, وَصَحَّحَهُ اَلتِّرْمِذِيّ ُ (1783)‏.‏ ‏1 ‏- صحيح.‏ رواه أحمد ( 5 / 7 ‏- 8 و 12 و 17 )‏، وأبو داود ( 2838 )‏، والنسائي، (7/166)‏، والترمذي (1522)‏، وابن ماجه (3165)‏ وقال الترمذي: "حديث حسن صحيح".‏

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also referenced under: Book 12, Hadith 1359 (In-Book)