The imagery of a mountain is HYPERBOLE.
Zechariah 4:7a, “Who are you, O great mountain? Before Zerubabel you shall become a plain.”
"The Jews used to set out those teachers among them, that were more eminent for the profoundness of their learning, or the splendour of their virtues, by such expressions as this; He is a rooter up (or a remover) of mountains. ‘Rabh Joseph is Sinai, and Rabbah is a rooter up of mountains.’ The Gloss: ‘They called Rabh Joseph Sinai, because he was very skillful in clearing of difficulties; and Rabbah Bar Nachmani, A rooter up of mountains, because he had a piercing judgment’ " (John Lightfoot, A Commentary on the New Testament from the Talmud and Hebraica, Hendrickson Publishers, Inc., Volume 2, p. 283.)