You searched for: “etiam si steterit in puteo
Non est magnus pumilio, licet in monte constiterit; colossus magnitudinem suam servabit, etiam si steterit in puteo. (Latin proverb)
Translation: "A dwarf is not tall, even though he stand on a mountain; a colossus keeps his height, even though he stand in a well."

From Seneca, Ad Lucilium Epis (c. A.D. 65).