Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos) By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
Second Section – the Negative Commandments
74. It is a negative commandment for a court “do not accept the testimony of a relative”
As it states in Devarim (Deuteronomy) 24:16, “do not put fathers to death because of children.” This means through the testimony of children. The same law applies for other relatives.
4. Be kind to yourself. Speaking badly even about yourself is unethical.
הלכות שמירת הלשון 