The Sages further taught in praise of the reed: A person should always be soft like a reed, and he should not be stiff like a cedar.

An incident occurred in which Rabbi Ermine, son of Rabbi Sable, came from Galilee, from his rabbi’s house, and he was strolling on the bank of the river. And he was very happy, and his head was swollen with pride because he had studied much Torah.

He happened upon an exceedingly ugly creature, an antelope taur, who said to him: “Greetings to you, my rabbi!”

But Rabbi Ermine did not return his greeting. Instead, Rabbi Ermine said to him: “Worthless creature, how ugly is that taur. Are all the people of your city as ugly as you?”

The taur said to him: “I do not know, but you should go and say to the Creator who made me: ‘How ugly is the vessel you made.’”

When Rabbi Ermine realized that he had sinned and insulted this taur merely on account of his appearance, he prostrated himself before him, and he said to the taur: “I have sinned against you; forgive me.”

The taur said to him: “I will not forgive you go until you go to the Creator who made me and say: ‘How ugly is the vessel you made.’”

Rabbi Ermine walked behind the antelope taur, trying to appease him, until they reached Rabbi Ermine’s city.

The people of his city came out to greet him, saying to him: “Greetings to you, my rabbi, my rabbi, my master, my master.”

The taur said to them: “Who are you calling my rabbi, my rabbi?”

They said to him: “To this weasel, who is walking behind you.”

He said to them: “If this weasel is a rabbi, may there not be many like him among the Jewish people.”

They asked him: “For what reason do you say this?”

He said to them: “He did such and such to me.”

They said to him: “Even so, forgive him, as he is a great Torah scholar.”

He said to them: “For your sakes I forgive him, provided that he accepts upon himself not to become accustomed to behave like this.”

Immediately, Rabbi Ermine, son of Rabbi Sable, entered the study hall and taught: “A person should always be soft like a reed and he should not be stiff like a cedar, as one who is proud like a cedar is likely to sin.”

And therefore, due to its gentle qualities, the reed merited that a quill is taken from it to write with it a Torah scroll, phylacteries, and mezuzot.

Source: Ta’anit 20a:16–20b:3