There is a difference between two things:
Firstly, reciting the Quran by moving the tongue without any sound. This recitation is considered valid in prayer and outside of it.
Secondly, looking at the Quran and moving the eyes without moving the tongue or making any sound, known as “reading with the eyes.” This is considered contemplation and reflection, and there is no ruling related to it. For example, reciting the Quran in the second way is not forbidden for a menstruating woman by the majority of scholars, unlike in the first way. If a person swears that he did not recite the Quran in the second way, he is not considered to have broken his oath, and he is not obliged to offer expiation because it is not considered recitation.
Moving the tongue is called recitation, while moving the eyes is called contemplation.
As far as I know, no jurist – based on what I have read – allows prayer or anything similar with contemplative recitation. Rather, everyone requires moving the tongue.
The default in recitation is to use the tools of recitation from the vocal apparatus, including the throat, tongue, lips, and so on. Moreover, there must be a minimum level of audibility, which is that the person should be able to hear himself or herself. Anything less than that is called mental speech, which is not considered valid in legal rulings. Allah says in the Quran: “Move not thy tongue concerning the (Qur’an) to make haste therewith. It is for Us to collect it and to promulgate it” (Al-Qiyamah, 75:16-17).
Therefore, whoever prays without using the vocal apparatus and without moving the tongue when required to do so is like someone who did not recite at all.
In general, recitation is one of the six pillars of prayer in our school of thought, and prayer is not valid without it.
And Allah knows best.
Fatwa by Dr. Khālid Naṣr