Thus there is a silence of the tongue, there is a silence of the whole body, there is the silence of the soul, there is the silence of the mind, and … - John of Apamea

Do not imagine, brother, that prayer consists solely of words, or that it can be learnt by means of words. No, the truth of the matter, you should understand, is that spiritual prayer does not reach fullness as a result of either learning or the repetition of words. For it is not to a man that you are praying, before whom you can repeat a well-composed speech: it is to Him who is Spirit that you are directing the movements of your prayer. You should pray therefore in spirit, seeing that He is Spirit.

And when you recite the words of the prayer that I have written for you, be careful not just to repeat them, but let your very self become these words. For there is no advantage in the reciting unless the word actually becomes embodied in you and becomes a deed, with the result that you are seen in the world to be a man of God—to whom glory, honour and exaltation is fitting, for eternal ages, amen.

It is in spirit and in mind, then, that he says that one should pray and sing to God; he does not say anything at all about the tongue. The reason is that this spiritual prayer is more interior than the tongue, more deeply interiorized than anything on the lips, more interiorized than any words or vocal song. When someone prays this kind of prayer he has sunk deeper than all speech, and he stands where spiritual beings and angels are to be found; like them, he utters ‘holy’ without any words. But if he cease from this kind of prayer and re-commence the prayer of vocal song, then he is outside the region of the angels and he becomes an ordinary man again.