DhammaPada verses 33-43 share on the mind and the importance of guarding it. The mind is compared to a fish out of water, and the wise one is encouraged to guard the mind to avoid falling into Māra's realm.

Citta vagga - Chapter 3 - Mind

33

Unstable and unsteady is the mind, difficult to guard and restrain; The wise one makes it straight, like a fletcher straightens an arrow.

34

Like a fish tossed on land, when pulled out from its home in the water; The mind trembles and shakes, struggling to escape Māra's realm.

35

Tricky to pin down and swift, landing wherever it wants; The taming of the mind is good, for the tamed mind leads to ease.

36

The mind is very subtle and hard to see, landing wherever it wants; The wise one should guard the mind, for a guarded mind leads to ease.

37

Wandering far and moving on its own, immaterial, dwelling in a cave; Those who restrain the mind, will be freed from Māra's bonds.

38

For one whose mind is unsteady, and who does not understand the true Dhamma; For one whose confidence wavers, wisdom does not reach fullness.

39

For one whose mind is not agitated, and whose thoughts are not afflicted; For one who has abandoned merit and demerit, there is no fear for the alert.

40

Having understood this body as being [fragile] like a clay pot, and fortifying this mind like a well-fortified city; One should fight out Māra with the sword of wisdom. Then guarding the victory, one should remain without attachment.

41

Before long, this body, will lie upon the earth; discarded and devoid of consciousness, like a useless log.

42

Whatever harm an enemy may do to an enemy, or a hostile person may do to another; a mind that is wrongly directed, inflicts on oneself greater harm.

43

Not even one's mother or father, or any other relatives; can do as much good, as a mind that is rightly directed.