This is the decree of the Torah (19:2)

זֹאת חֻקַּת הַתּוֹרָה וגו': ספר במדבר פרק י"ט פ"ב

Chukoh (decree) is from the language of Chakikoh (engraved). The Torah is obligatory to be engraved in the heart of a person – Zos Chukas HaTorah.

• Sefer Ba’er Moshe – Sefer Pininei HaTorah