John Lightfoot on John 5:35

[A burning and a shining light.] He speaks according to the vulgar dialect of that nation; who were wont to call any person famous for life or knowledge a candle. "Shuah" [the father-in-law of Judah, Genesis 38] "was the candle or light of the place where he lived." The Gloss is, "One of the most famous men in the city enlightening their eyes." Hence the title given to the Rabbins, the candle of the law: the lamp of light.