The intent to remove is written in Ben-Gurion’s own hand, in a letter to his son Amos dated 5 October 1937, held in the Ben-Gurion Archives and translated into English by the Institute for Palestine Studies in Beirut. Arguing that the Negev could not be left in Palestinian hands, he wrote:
We must expel Arabs and take their place. Up to now, all our aspirations have been based on an assumption — one that has been vindicated throughout our activities in the country — that there is enough room in the land for the Arabs and ourselves.
That passage is contested and the contest should be on this page rather than discovered afterwards. Lines immediately before it are struck through in the manuscript, and the pro-Israel media group CAMERA has argued that the struck text reverses the meaning. The Electronic Intifada put the Hebrew to two professional translators and a linguist independently; all three rejected that reading. Two of them, however, agreed with CAMERA on a separate point that bears directly on the words quoted above: that the English “up to now” and “but” were inserted by the translators and are not explicit in the Hebrew — Daniel Shunra calling the insertion “regrettable, though immaterial and blown out of proportion.” We print the translation as published and record the objection to it, and one noted that the sentence carries a grammatical idiosyncrasy characteristic of Ben-Gurion — the missing object particleet — which a forger would have had to know to imitate. Readers can and should read the whole letter; it is linked below in full.
As for forgetting specifically, the closest sourced formulation Winstanley’s inquiry surfaced is Avi Raz’s citation of Tom Segev’s 1949: The First Israelis, page 31, where Ben-Gurion is described as holding that the refugee problem would solve itself: “In his opinion … time will cure all, and all will be forgotten.” We have not read Segev directly and we present it at that remove, which is exactly the standard the famous quotation fails.