Parashas Kedoshim · Passuk 19:03
Chabad.org — English translation + Rashi
Torah Temimah · Kiddushin 30b.
English: It is said “his mother and his father you shall fear” and it is said “Hashem your God you shall fear” — from here Scripture equated the fear of father and mother with the fear of Heaven.
Equation of parental mora with mora of the Makom
The Torah places mora av va-em on the same plane as mora Shamayim, reflected also in parallel punishments (e.g. cursing a parent and cursing Hashem).