Reference for Ketubot 54:13

לימא כתנאי זו עדות איש ואשה תינוק ותינוקת אביה ואמה ואחיה ואחותה אבל לא בנה ובתה לא עבדה ושפחתה ותניא אידך הכל נאמנין להעיד חוץ מהימנה ובעלה

Shall we say that this difference is like that between [these] tannaim? [For it was taught]: This testimony: a man and a woman, a boy and a girl, her father and her mother, her brother and her sister [may testify], but not her son and her daughter, nor her slave and her handmaid. And in another [baraita] it was taught: All are believed to testify [for her] except herself and her husband.

Jastrow