Indulge a child for the first five years of his life, for the next ten years deal firmly with the child. Once the child is sixteen, treat him as a friend.
[lAlayEth pancha varSHANi dasha varSHANi thAdayEth / prApthE thu SHOdashE varSHE puthram mithravadh AcharEth //
लालयेत् पञ्च वर्षाणि दश वर्षाणि ताडयेत् / प्राप्ते तु षोडशे वर्षे पुत्रं मित्रवदाचरेत् //]
A variant of these shloka is this from the Mahaa-nirvaaNa-tantra:
caturvarSAvadhi sutA.NllAlayet paalayet pitaa. tataH SoDashparyantaM guNAn vidyAM ca shikSayet..
चतुर्वर्षावधि सुताँल्लालयेत् पालयेत् पिता।
ततः षोडशपर्यन्तं गुणान् विद्यां च शिक्षयेत्॥