Musar zu Tehillim 140:10

And now, let us conclude the book as we began, with the verse (Psalms 34:13): "Who is the man who desires life, who loves days to see good?", by introducing my explanation of the verse (Psalms 140:12): "The man of the tongue will not be established on the earth. The man of violence — evil will hunt him to his downfall." We shall preface this by a general introduction to this work. In sum, one who truly wishes to guard his mouth and his tongue, in order not to come to machloketh [contention] and lashon hara and cursing and "whitening of the face" will acquire for himself with full payment the trait of patience, to "overlook his traits" in all regards. That is, to acquiesce within himself that for this holy trait he will expend every year about four or five silver rubles. And, for a richer man, a larger sum, as will be explained.