Be careful with his tarbiyyah
Ibn al-Qayyim رحمه الله said in Tuhfat al-Mawdood (240):
One thing that the child desperately needs is for care to be taken with regard to his morals and attitude, for he will grow up with whatever the one who is raising him accustoms him to when he is small, and when he grows older it becomes difficult for him to change what he has got used to; these attitudes and characteristics that have become deeply ingrained in him, even if he tries to suppress them, they will always surface and expose him.
ابن القيّم رحمه الله في "تحفة المودود" (240) :
" ومما يحتاجُ إليهِ الطفلُ غايةَ الاحتياج الاعتناء بأمرِ خلْقهِ ، فإنهُ ينشأ على ما عوّدهُ المربي في صغره ، فيصعبُ عليه في كبرهِ تلافي ذلك ، وتصيرُ هذهِ الأخلاق صفاتٍ وهيئاتٍ راسخةً له ، فلو تحرّزَ منها غايةَ التحرزِ فضحته ولا بد يومًا ما "