Co-equal With the Father

I and my Father are one. John 10:30

"The age of 30 was the age of maturity, of “adoption” and of priesthood. At this age, a Jewish Father would take his first born son, take him to the city gate at which sat the leaders of the city and declare him co-equal in their business. The word of the son would be the same as if speaking to the father. They were one."

(I lost the reference for this info--sorry.)