This is not “extremism”; it is mainstream Islam. The notorious genocidal hadith states: “Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: The last hour would not come unless the Muslims will fight against the Jews and the Muslims would kill them until the Jews would hide themselves behind a stone or a tree and a stone or a tree would say: Muslim, or the servant of Allah, there is a Jew behind me; come and kill him; but the tree Gharqad would not say, for it is the tree of the Jews.” (Sahih Muslim 6985)
This hadith is repeated with minor variants several times in the hadith literature, which repetition Islamic scholars take to be a sign of authenticity.
“In Nablus Friday Sermon, Sheikh Muhammad Nour Malhas: People Who Normalize Relations with Israel Will Not Be Among Muslims to Kill Jews on Judgement Day,” MEMRI, August 17, 2019:
In an August 16, 2019 Friday sermon at the Kawthar Badran Mosque in Nablus, Palestinian Sheikh Muhammad Nour Malhas cited an antisemitic hadith that says that the Muslims will fight and kill the Jews on Judgement Day and that the Jews will hide behind rocks and trees, which will call out to the Muslims to kill the Jews hiding behind them. Sheikh Nour pointed out that the hadith refers to “servants of Allah,” and he said that this serves to exclude hypocrites and Muslims who normalize relations with Israel. He added a prayer asking Allah to make the congregation from among His mujahideen and murabiteen.
Sheikh Muhammad Nour Malhas: [The Prophet Muhammad said:] “You will fight the Jews, and you will kill them. They will hide behind rocks, but the rocks and the trees will say: ‘Oh Muslim, oh servant of Allah’…” Note that the term that is used is “Muslim, servant of Allah.” This isn’t just anyone – not a hypocrite or someone who normalizes relations [with Israel]. “[The trees and rocks will say:] ‘Oh Muslim, oh servant of Allah, there is a Jew hiding behind me, come and kill him.'” Oh Allah, make us from among your mujahideen and murabiteen servants.