Bede

And they sat on the first day of the tenth month, etc. Note that the number three is very commonly used in mystical figures. It was previously said that in three days all the sons of the diaspora should come to Jerusalem; and now in three months, namely the tenth, eleventh, and twelfth, they are punished by foreign wives. For there are three virtues without which we cannot attain life: faith, hope, and charity. Coming into the world at the third time of the age, the Lord bestowed upon us the grace of the Gospel. …

Commentary on Ezra and Nehemiah ↗