Your toes must touch the ground and should be bent while pointing to the Ka’abah. That is why it is wrong to be erect on the ground. They should be bent.

10 When we go in sujood, should all our toes touch the ground or is it okay if only one or two toes touch the ground while the other toes do not (if for instance, the shape of the foot is arched and it is not possible for all ten toes to touch the ground). Once, I had heard a Sheikh saying that all the toes should touch the ground. Please enlighten us on this matter.