In his later years, he was concerned about the capacity of his child Mitsutokumaru (later Tadayuki KURODA), and provided him with many family precepts (some say the gojosoku was invented in a later age).
晩年には子の満徳丸（後の黒田忠之）の器量を心配して、いくつもの家訓（御定則）を与えている（御定則は後世の創作であるとも）。