Not in these words, and perhaps not in this sense. Heraclitus's book is lost; his sayings survive only as quotations in later writers. Plato, in the Cratylus (402a), reports that Heraclitus said you cannot step twice into the same river. But the fragment most scholars accept as Heraclitus's own wording says: “On those stepping into rivers staying the same other and other waters flow.” The popular second half, “for it's not the same river and he's not the same man”, has no ancient source.
What it means
Everything changes, including us. The usual reading is that nothing stays the same long enough to be met twice. The subtler reading of the surviving fragment is that some things stay the same only by changing, as a river stays a river because its water keeps moving.
Where it comes from
In Plato's Cratylus Socrates says: “Heracleitus says, you know, that all things move and nothing remains still, and he likens the universe to the current of a river, saying that you cannot step twice into the same stream” (Fowler's translation). Plutarch, centuries later, gives a similar line. These are reports, not quotations, and the Stanford Encyclopedia of Philosophy notes that of the three “river fragments” only one (numbered B12) has the dense, double-edged style of Heraclitus's own words.
B12, as the Stanford Encyclopedia translates it, says that other and other waters flow on those who step into the same rivers: the rivers stay the same while the water changes. On that reading Heraclitus was not saying you cannot step in twice, but that sameness and change go together. The encyclopedia suggests the stronger version may come from a misreading by Cratylus, a later follower whose lectures Plato is said to have heard. We found no ancient source for the familiar addition about the man not being the same.