After the failure of the 1921 Syrian revolt that he led, al-Qassam escaped to Haifa. According to Shai Lachman, between 1921 and 1935 al-Qassam often cooperated with Mufti of Jerusalem Mohammad Amin al-Husayni. They were on good terms, and al-Qassam's various official appointments required the mufti's prior consent. He suggests their cooperation increased after the 1929 riots, in which one source claims al-Qassam's men were active. The two fell out in the mid-thirties, perhaps due to al-Qassam's independent line of activism. When the Mufti rejected his plans to divert funding marked for mosque repairs for the purchase of weaponry, Qassam found support in the Arab Nationalist Istiqlal Party. Qassam continued his attempts to forge an alliance with the Mufti in order to attack the British. He was not successful for the Mufti, who headed the Supreme Muslim Council, was still committed to a diplomatic approach at the time. Qassam went ahead with his plans to attack the British on his own.