Siman 496

(53.) Once they were speaking before him about greatness. He answered and said: "What do you need to speak about greatness? I have no greatness!" (Meaning: and how could it occur to you that you could have any greatness — since even I have no greatness?) For Rabbainu o.b.m. had already boasted of this — that he can say about himself that he has no greatness. For this is the ultimate, complete perfection of humility — like the aspect of Moses our teacher who wrote about himself [Numbers 12]: "And the man Moses was very humble." As is cited in the Gemara [Sotah 49b] that he said...