mishkat 20 Game and Animals Which May Be Slaughtered كتاب الصيد والذبائح 16
وَعَن أنس قَالَ: غَدَوْتُ إِلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بِعَبْدِ اللَّهِ بْنِ أَبِي طَلْحَةَ لِيُحَنِّكَهُ فَوَافَيْتُهُ فِي يَدِهِ الْمِيسَمُ يَسِمُ إِبِلَ الصَّدَقَة
Anas told that one morning he took ‘Abdallah b. Abu Talha to God’s messenger for him to chew something and rub his palate with it,* and found him with a branding-iron in his hand branding the camels of the sadaqa . *This was a custom for the purpose of acquiring a blessing for children. (Bukhari and Muslim.)