Is it a condition to move the tongue when reciting the Quran and performing adhkar, and what is the most preponderant opinion regarding the preference of dhikr by heart or by tongue, and is it permissible to perform dhikr by heart only?

It is permissible to perform dhikr (remembrance of God) by heart in all its forms. However, for devotional acts of remembrance such as Al-Fatiha, Takbirat al-Ihram (the opening Takbir of prayer), and the remembrances within prayer, dhikr by heart is not sufficient. Rather, it is necessary to move the tongue with them, and the majority of scholars stipulate that the reciter must hear himself.