One distinctive feature of Chopin’s playing was his rubato.
Chopin’s friend and student Wilhelm Von Lenz said: “A remarkable feature of his playing was the entire freedom with which he treated the rhythm, but which appeared so natural that for years it had never struck me. It must have been in 1845 or 1846 that I once ventured to observe to him that most of his mazurkas (those dainty jewels) when played by himself appeared to be written not in 3/4 but in 4/4 time, the result of his dwelling so much longer on the first note of the bar. He denied it strenuously, until I made him play one of them and counted audibly four in the bar, which fitted perfectly. Then he laughed and explained that it was the national character of the dance which created the oddity.”
On the same topic of rubato, Salaman wrote after hearing Chopin play in 1848: “in spite of all I had heard of Chopin’s tempo rubato, I still recollect noting how precise he was in the matter of time, accent and rhythm, even when playing most passionately, fancifully and rhapsodically.”