With accent marks:
У семи́ ня́нек дитя́ без гла́зу.
~ Seven babysitters make the kid to lose an eye.
The more people take on one task, the less attention is paid to the task.
The closest English equivalent: too many cooks spoil the broth.
Other Russian proverbs
There is no smoke without fire.
A titmouse in hands is better than a crane in the sky.
The eyes are scared, but the hands are doing.
A bird is visible by its flight.
Man does not live thanks to bread alone.
Trust but verify.
Time for business, an hour for fun.
Live for a century, learn for a century, but die being a fool anyway.