Silent Psalms

Ἔξεστι καὶ χωρὶς φωνῆς ψάλλειν, τὴς διανοίας ἔνδον ἠχούσης. Οὐ γὰρ ἀνθρώποις ψάλλομεν, ἀλλὰ Θεῷ τῷ δυναμένῳ καὶ καρδίας ἀκοῦσαι, καὶ εἰς τὰ ἀπόῥῥητα τῆς διανοίας ἡμῶν εἰσελθεῖν. Καὶ ταῦτα Παῦλος ἐνδεικνύμενος Βοᾷ, λέγων· 'Αὐτὸ τὸ Πνεῦμα ἐντυγχάνει ὑπὲρ ἡμῶν στεναγνοῖς ἀλαλήτοις. Ὁ δὲ ἐρευνῶν τὰς καρδίας, εἶδε τὶ τὸ φρόνημα τοῦ Πνεύματος, ὅτι κατὰ Θεὸν ἐντυγχάνει ὑπὲρ ἁγίων.' Τοῦτο δὲ ἔλεγεν, οὐκ ἐπειδή τὸ Πνεῦμα ἐστέναζεν, ἀλλ' ἐπειδὴ οἱ πνευματικοὶ ἄνδρες, οἱ τὰ χαρίσματα τοῦ Πνεῦματος ἔχοντες, ὕπὲρ τῶν πλησίον εὐχόμενοι, καὶ τὰς ἱκετηρίας ἀνανφέροντες, μετα κατανύξεως καὶ στεναγμῶν τοῦτο ἐποίουν. Τοῦτο καὶ ἡμεῖς ποιῶμεν, καὶ καθ' ἐκάστην ἡμέραν ἐντυγχάνωμεν τῷ Θεῷ διά τε ψαλμῶν καὶ εὐχῶν. Εἰς Τον ΜΑ' Ψαλμον, Ἅγιος Ἰωάννης ὁ Χρυσόστομος

It is permitted to sing psalms without using the voice, when they resound within the mind. For we do not sing to men but God, He who is able to hear the heart and come in secret into our minds. This also Paul shows openly, saying ' The Spirit himself will speak for you with groans ineffable. He who scrutinises the heart knows the Spirit's intention, for according to God he asks for the saints.' 1 And it was said not that the Spirit groans, but that spiritual men, who have the gift of the Spirit, praying for others, and offering supplications, that they do this with compunction and groaning. This then we may do, even every day, in our calling on God with psalms and prayers. Exposition of the Psalms, Psalm 41, Saint John Chrysostom 1 Rom 8 26-27