It turns out the Mufti of Jerusalem was not the first one to incite Arabs against Jews by claiming they intended to destroy the Dome of the Rock or Al Aqsa in the 1920s.
While there is some indication of general warnings about Jews buying property in the area of the Mount in the 1880s and 1890s, the earliest specific mention of Arabs accusing Jews of having designs on the Temple Mount comes from around 1903, mentioned in
The Arabs and Zionism before World War I by Neville J. Mandel (1976) where he recounts an anecdote published in Alliance Israelite Universelle saying "a young (and, it was noted, not very extreme) Muslim told a Jew in Jerusalem: '
We shall pour out everything to the last drop of blood rather than see the Dome of the Rock fall into the hands of non-Muslims.' ”
Since this came from an ordinary Arab in Jerusalem that means that the idea had already been pushed by Arab and Ottoman leaders for at least some years beforehand. (I'm still looking for earlier primary sources; an 1891 telegram from Jerusalem Arab notables to Ottoman leaders may have mentioned Jewish religious ambitions along with economic warnings about Jewish immigration.)
It has been one of the most effective antisemitic propaganda methods for over 125 years, and now with the Iran war we are seeing it being exploited daily.
Yesterday, the head of the Supreme Islamic Council in Jerusalem and preacher of Al-Aqsa Mosque,
Sheikh Ekrima Sabri, warned of a "dangerous plan" targeting the mosque.
French Arabic site
Aqlame has a columnist saying:
The fall of Iran, or its suffering a severe strategic defeat, would undoubtedly mean—from our perspective today—the removal of one of the biggest geopolitical obstacles to this [Third Temple] project. For years, Iran has been seen as the most vocal regional power in defending the Al-Aqsa Mosque, and it has adopted a political and religious discourse that links Jerusalem to the conflict with Israel on the level of identity and civilization.
The Greater Israel project cannot be realized without the construction of the Third Temple; this is a clear geostrategic fact. For Benjamin Netanyahu, the Temple is what will achieve symbolic balance among the major religious and cultural centers, alongside Mecca and the Vatican. Ignoring this point in Islamic political discussions, if not out of ignorance, is either negligence or fear.
Palestinian site Madar News took a
joke post by Jewish right wing activist Baruch Marzel seriously as a method to get Iran or Israel to attack the Dome of the Rock.

It reports that the Palestinian "Jerusalem Governorate"
stated on Saturday that the extremist rabbi Baruch Marzel published an AI-generated image showing an aircraft base under the Al-Aqsa Mosque, accompanied by a sarcastic comment claiming the existence of a “secret air force base in Jerusalem,” in a move considered a dangerous incitement that paves the way for justifying targeting the Al-Aqsa Mosque .
It is amazing that Israel has held off on demolishing Al Aqsa and the Dome of the Rock for so many years but now the only thing stopping it is Iran. Usually the excuse is Palestinian steadfastness.
The "Al Aqsa is in Danger" meme is one of the most durable slanders, used cynically by Muslim leaders for over a century to incite antisemitism. And it works, even today.