Prophet (SAW)'s Prayers When the child begins to talk

Recite:

لَا إِلَهَ إِلَّا اللَّهُ

and the following Ayah of the Qur'an first:

وَقُلِ الْحَمْدُ لِلَّهِ الَّذِي لَمْ يَتَّخِذْ وَلَدَاً وَلَمْ يَكُنْ لَهُ شَرِيكٌ فِي الْمُلْكِ وَلَمْ يَكُنْ لَهُ وَلِيٌّ مِنَ الذُّلِّ وَكَبِّرْهُ تَكْبِيرَاً

"Say that All praise belongs to Allah who has no children nor any partner in His ownership, nor any dependent, and in the proper manner we mention His greatness". (Hisnul Hasin)