Iggeret HaRamban

“Listen, my son, to the thought of your father, and do not forsake the teaching of your mother.” (Proverbs 1:8)

Accustom yourself to always speak all of your words calmly, to every man and at every time. In doing so you will prevent your anger from flaring, which is a bad attribute in a man which may cause him to sin. And accordingly said our Rabbis, may their memories be a blessing: (Nedarim 22a) “Anyone who gets angry - all of Gehinnom holds sway over him, as it says: (Kohelet 11:10) ‘And remove the anger from your heart, and take away the bad from your flesh’, and ‘bad’ can only mean Gehinnom, as it says (Proverbs 16:4): ‘And the sinner, he too, will have his day of bad’.”

When you will have freed yourself from anger, the quality of humility will enter your heart which is the best of all good traits, as is written(Mishlei 22:4), “The return for humility is fear of G-d.”

Through humility you will also come to fear God. It will cause you to always think about (Pirkei Avot 3:1) “where you came from and where you are going,” and that while alive you are only like a maggot and a worm as after death, and before Whom you will eventually stand for judgment, the Glorious King, as it is written (I Kings 8:27) (Chronicles II 6:18) “Even the heaven and the heavens of heaven cannot contain You” — “How much less the hearts of people!”(Mishlei 15:11), It is also written (Jeremiah 23:24), “Do I not fill heaven and earth? says the Lord.”