Proverbs 4:20-23
20 My son, attend to my words; incline thine ear unto my sayings.
21 Let them not depart from thine eyes; keep them in the midst of thine heart.
22 For they are life unto those that find them, and health to all their flesh.
23 Keep thy heart with all diligence; for out of it are the issues of life.

Proverbs 4:23 Keep thy heart with all diligence; for out of it are the issues of life.