In this the PA is simply reflecting traditional Islamic piety. The Hadith quoted by Dr. Hassan Khater is repeated several times in Sahih Muslim, indicating its attestation by multiple sources. (The exact version he quotes is in book 41, no. 6985). Nor is he the first Palestinian official to quote it.
From Palestinian Media Watch (no direct link), with thanks to JC:
For years, the PA religious establishment has repeatedly portrayed the killing of Jews as a religious necessity. Today, PA TV chose to rebroadcast this same call to genocide as a historical necessity — this time from a senior PA academic rather than from a religious leader. Dr. Hassan Khater, founder of the Al Quds Encyclopedia and a TV lecturer, cited the identical Hadith – Islamic tradition attributed to Mohammed – that the religious leaders have used to demand this genocide. This was part of a lecture focusing on what he described as the war of the Jews against Palestinian trees.
These were his words quoting the Hadith:
“Mohammed said in his Hadith: ‘The Hour [Day of Resurrection] will not arrive until you fight the Jews, [until a Jew will hide behind a rock or tree] and the rock and the tree will say: Oh Muslim, servant of Allah, there is a Jew behind me, come and kill him!'” PA TV Dec. 27, 2004 [Rebroadcast from July 13, 2003]
The continued teaching that this Hadith applies today could well be a dominant factor driving terror against Israeli civilians. By depicting redemption as dependent on Muslims’ killing of Jews, the PA world view presents this genocide as a religious obligation and historical necessity — not related to the conflict over borders, but as something inherent to Allah’s world.