I remember several times coming across a text that asked something along the lines of:
"Who should one seek/learn Torah from?"
or
"How does one know whether to seek/learn Torah from a certain Rabbi?"

And the answer being something along the lines of:
"One who's face is glowing, appearing joyous or as an angel, that's how you tell that he is who you should learn from."

Has someone come across this that could point me to the source?
Thanks in advance.