The 230th prohibition is that we are forbidden from collecting debts in the shemittah year; they must be completely released.
The source of this prohibition is G‑d's statement,1 "Every creditor shall remit any debt owed by his neighbor. He may not collect from his neighbor or his brother."
This is a Biblical commandment only in Eretz Yisrael when the mitzvah of shemittah of the land — i.e., the jubilee year — is in effect. However, there is a Rabbinic prohibition in effect at all times and in all places. Therefore, one may not collect a debt once the shemittah year has passed; it must be released.
The details of this mitzvah are explained in the end of tractate Sh'vi'is.
