A peaceful and joyful night for you

if you consider the finite group of rationals modulo p resp. u/v mod p element of Q/Z

Is u/v a non quadratic residue,

if jacobi (u²+v², p)=-1 or

if jacobi (u, p)*jacobi (v, p)=-1

A short answer, perhaps with a little explication, would be very nice and perhaps also interesting for other members.