Likutei Moharan 51:1/ליקוטי מוהר"ן נ״א:א׳

1Amar Rebbi Akiva (Rabbi Akiva said): When you approach pure marble stone, do not say, “Water! Water!” as it is said (Psalms 101:7), “He who speaks falsely will not be sustained before My eyes.” (Chagigah 14b)

2Falsehood is harmful to the eyes, physically and spiritually, in the aspect of “The eyes deceive” (Isaiah 3:16). For when the eyes are dimmed, they create false impressions. They do not show a thing as it really is; for example, a large object appears small, and one [object appears] as if it were two—the very opposite of the truth.

3This is because the eyes become dimmed by tears. As our Sages taught: “The clouds return after the rain” (Ecclesia st es 12:2)—this refers to the vision, which is diminished after crying (Shabbat 151b). Tears stem from excess melancholy, which nature expels by way of the eyes. And melancholy stems from polluted blood.

4And the blood is polluted by falsehood. It is impossible for a person to speak falsely unless he has already polluted his blood, just as it is impossible to speak truthfully unless he first purifies the blood. This is because the essence of speech is the soul, as is written (Song of Songs 5:6), “My soul went out when he spoke.” And the soul is the blood, as is written (Deuteronomy 12:23), “for the blood is [associated with] the soul.” We see then that when a person speaks falsely, his blood is polluted. It is this that gives rise to melancholy. And from the excess melancholy, tears are formed, causing the eyes to become dimmed.

5This corresponds to “They pluck the saltwort from the SIaCh (shrubs)” (Job 30:4). “Saltwort” is the aspect of tears, which are the salty water that comes from SIChah (speaking).

6This also corresponds to “Do not say, ‘Water! Water!’”—a warning against falsehood. {As is concluded there: “as it is said, ‘He who speaks falsely will not be sustained before My eyes.’”}

7“Water! Water!” is the aspect of falsehood, which is the aspect of tears, salty water. For when a person drinks water, he quenches his thirst. Yet when he drinks salty water, not only does he not relieve his thirst, but he increases it. He then has to drink other water in order to quench his thirst. This is why falsehood is referred to as “Water! Water!”

8This is the explanation of “Do not say, ‘Water! Water!’” which is falsehood, “as it is said, ‘He who speaks falsely will not be sustained before My eyes.’”