Is it permissible to make a vow to abandon a sin, knowing that one will return to it after the vow's term expires?

The scholars differed concerning a vow to abandon sin. Many of them held that such a vow is not binding because it is an obligation in the first place. Others maintained that it is binding and that whoever breaks it must offer an expiation for a broken oath.

What is obligatory upon you is to strive against your soul to abandon sin, to hasten to repentance and seek forgiveness, and to resolve not to return to it if you commit it. You are not required to offer an expiation according to many scholars. However, it is more cautious to offer an expiation for a broken oath (feeding ten poor persons, or clothing them, or freeing a slave, or fasting three days if you cannot find any of the former).