"Solidarity is a verb not a noun," Sarsour wrote in a viral Facebook post.
Sarsour said she felt "outraged at the despicable act committed against the St. Louis Jewish cemetery," and called upon the Muslim community to help rebuild it.
"We are also inspired by the example of our Prophet Muhammad, peace be upon him, who stood up to pay respects for a passing Jewish funeral procession," she wrote. "When questioned on why he stood for a Jewish funeral, he responded, 'Is it not a human soul?'"
People are thanking Sarsour, El-Messidi, and all who contributed to the campaign, many citing Sarsour's statement that "solidarity is a verb."
Police are reviewing security footage of the cemetery, but have not yet made any arrests, the St. Louis Post-Dispatch reported.
The vandalism incident follows a series of bomb threats on Jewish Community Centers across the country, including 11 just this past weekend, all of which were determined to be hoaxes.
In response to the bomb threats, the Council on American-Islamic Relations, an American organization for Muslim civil rights and advocacy, is offering a $5,000 reward for information leading to the arrest of those who made the bomb threats.
"It is the duty of American Muslims to offer support to the Jewish community and any minority group targeted in the recent spike in hate crimes nationwide,” CAIR National Executive Director Nihad Awad said in a statement.
“We hope this reward will aid in the swift apprehension and prosecution of the perpetrators.”
BuzzFeed News has reached out to Sarsour and El-Messidi.