According to 'Zoku kojidan,' since his father KAMO no Yasunori taught the art of astronomy exclusively to ABE no Seimei, he ended up only inheriting the art of calendar making, which caused him to view ABE no Seimei as his rival.
父・賀茂保憲が天文道を安倍晴明に伝授禅譲したために暦道のみを継承することとなり、これが原因で安倍晴明をライバル視していたことが「続古事談」に記されている。