Reference: Fataawa wa Rasaa.il Mukhtaarah – Page 534
Question: What is the ruling regarding smacking a young child of four years of age? And what is the ruling regarding lying to him? Please provide us with a legal religious verdict and may you be rewarded.
Response: It is not befitting to smack a small child who is of such an age; That is because he is unable to differentiate between right and wrong. Once, Umm Sulaym came to the Messenger of Allaah ﷺ with [her son] Anas and said: “O Messenger of Allaah! This is my son Anas (as she affectionately called him), I have brought him to you so that he may serve you” – transmitted by Muslim.
And Anas ibn Maalik (radhi-yAllaahu ‘anhu) said: “I Served the Prophet ﷺ for ten years, and he never [even] said “uff” to me, nor “why did you do that!”, and nor “haven’t you done that [yet]”.” – transmitted by al-Bukhaaree.
So if the Prophet ﷺ has not commanded to smack [a child] for a major thing like as-salaah until the child reaches ten years of age, then how can he be smacked for other than that whilst he is only four years of age?!
As for lying to them, then it is not permissible as the Prophet ﷺ has prohibited that.
And with Allaah lies all success.