Не видит сова, какова сама

See Веника не переломишь, а по пруту весь веник переломаешь b (В), Других не суди, на себя погляди (Д)

Cf: The eye that sees all things else sees not itself (Br.). The eye that sees all things sees not itself (Am.). A hunchback cannot see his hunch (Am.). The hunchback does not see his own hump, but sees his companion's (Br.). The hunchback only sees the hump of his neighbor (Am.)