Shaykh (Al-Mufid), may Allah سبحانه وتعالى have mercy on him, said: “And if the deceased is a child, then say after the fourth takbir: ‘O’ Allah سبحانه وتعالى, this child, as You سبحانه وتعالى created him capable and took him while pure, so make him a light for his parents and grant us reward through him and do not subject us to tribulation after him’.
Commentary #11