If you have foreign thoughts when you pray, G‑d forbid, the “impure shell”¹¹; i.e. a force of unholiness. rides on your words; for thought rides upon speech. This is the meaning of: “to the horses in the chariot of Pharaoh, I have compared you, my beloved” (Song of Songs 1:9). Speech is called “horses,” and when Pharaoh – the foreign thought – rides upon it, then “I have compared you (“dimisicha”), my beloved.” For it would be better to be silent.¹²” is “domeh,” which is related to the word dumiah –”silence.” Thus, at a time when foreign thoughts ride on one’s words of prayer, it would be better to be silent. However, “a word that comes from the heart, enters the heart” – that is, the Supernal Heart, by means of the breath, as is known. Tzava’as HaRivash, p. 8a

footnotes: ¹¹ Kelipah ¹² The grammatical root of the word “dimisicha