And Adonai said, Inasmuch as this people approached with its mouth and with its lips honored Me but kept its heart far from Me, and their reverence for Me was a commandment of men learned by rote, therefore will I continue to strike this people with wonder upon wonder, and the wisdom of its wise men shall vanish and the discernment of its discerners disappear (Isaiah 29:13–14).
“There is service of the blessed Holy One based on activity of the body, and this is considered service. Then there is service of the blessed Holy One that is more internal, and this is essence, for all depends on that inner service, essence of all” (Zohar 2:201a).
“Do not stand לְהִתְפַּלֵּל (le-hitpallel), to make yourself the object of [divine] intervention, unless with deep concentration [lit., מִתּוֹךְ כֹּבֶד רֹאשׁ (mitokh koved rosh), in the midst of a heavy head, cf. BT Yevamot 105b]. The devout men of old used to wait one hour before praying in order to direct their heart-minds to the Omnipresent—even if a king greets him, he should not answer; even if a serpent is wound round his heel, he should not break off” (M Berakhot 5:1, cf. BT Berakhot 30b).
“Rabbi Yirmiyah said in the name of Rabbi El’azar, ‘One who was reciting the [Amidah] Prayer וְלֹא כִּיוֵּן לִבּוֹ (ve-lo kivven libbo), but his mind was not focused, if he knows that he can go back and focus he should go back and recite the Prayer. And if not, he should not go back and recite the Prayer.’
Rabbi Ḥiyya the Great said, ‘In all my days I never כִּוּוּנִית (kivunit), focused. One time I wanted to focus וְהִרְהֲרִית בְּלִבִּי (ve-hirharit be-libbi), and I conceived in my mind. And I said to myself, ‘Who goes up first before the king? The Arqabata [a high dignitary in Persia] or the Exilarch?’
Shemu’el said, ‘I count the birds [or: clouds].’
Rabbi Bun son of Ḥiyya said, ‘I count rows of bricks.’ Rav Matanyah said, ‘I regard myself as profited. For when I reach the Thanksgiving blessing, my head bows instinctively’” (JT Berakhot 2:4, 17b).
“Merit has both stock and fruit, as is said: It is good for the righteous [for the fruit of his deeds he enjoys] (Isaiah 3:10). Transgression has stock but not fruit, as is said: Alas, for the wicked, there is evil, [for as his hands have done, it will be done to him] (ibid., 11). Then how do I establish, And they ate from the fruit of their way, and from their own counsels they were sated (Proverbs 1:31)? Transgression which bears fruit has fruit; that which does not bear fruit has no fruit.
A good thought is linked with action, as is said: Then did the YHWH-fearers speak together, each man to his neighbor, and YHWH hearkened and He heard, and a book of remembrance was written before Him for the YHWH-fearers who value His name (Malachi 3:16). Now, what is who value His name [lit., וּלְחֹשְׁבֵי (u-le-ḥoshvei), and that thought upon, His name]?
Rav Assi said: Even if one [merely] thinks of performing a mitsvah but is forcibly prevented the verse ascribes it to him as though he has performed it. An evil thought is not linked with action, as is said: Had I seen mischief in my heart, Adonai would not have listened (Psalms 66:18). Then how do I establish, [Hear, O earth,] I am about to bring evil against this people, the fruit of their devisings [for they did not listen to all My words, and My teaching they have spurned] (Jeremiah 6:19)? Thought which bears fruit the blessed Holy One links with action. Thought which does not bear fruit the blessed Holy One does not link with action.
What of So as to catch the house of Israel in their thoughts (Ezekiel 14:5)? Rav Aḥa son of Ya’aqov: That refers to idolatry, for a Master said: Idolatry is so heinous that he who rejects it is as though he admits [the truth of] the whole Torah. ‘Ulla said: [This is to be explained] as Rav Huna taught. For Rav Huna said: Once a man transgresses and repeats it, it is permitted him. ‘It is permitted him!’ can you really think so? Rather, it becomes to him as something permitted [cf. BT Yoma 39a: ‘Transgression dulls the heart of man]” (BT Qiddushin 40a).