זוהר שמות — דף ריח ע”א

Boaz saw through the holy spirit that Ruth had a good eye (ayin tova): everything she looked at was blessed and everything she gathered increased in the field. He saw in her the eyes that guide everything, as ruling kings were destined to come from her. The field is Zion and Jerusalem, for from Zion the Torah goes forth. The righteous are called vessels of God, broken in this world in order to uphold the Torah and bring a gift to the messianic king.