What is the appropriate age to teach one's son Islam as a way of life, and what are the recommended books to start with?

The Islamic education of a child begins at birth with the recitation of the Adhan in their ear, followed by the declaration of Tawhid, "La ilaha illa Allah" (There is no god but Allah). Love for Islam is instilled in their heart with gentleness and kindness, and by teaching them what benefits them in their religion and worldly life, such as good manners and beneficial physical sports. The best thing to teach a child once their tongue is articulate is the Holy Quran, then prayer at the age of seven, while continuing to learn the Quran and Sunnah. This education should be conducted with gentleness, taking into account the child's capacity and mental readiness.