Ani Ma'amin
I came across a video of a Purim celebration in Tel Aviv on Mar 14 2025. The party looks like any generic non-religious party you would expect.
To my surprise, however, the crowd was singing something messiach (messiah) around 0:32.
After a bit of searching, it turns out the crowd is most likely singing the Ani Ma'amin (1915) song by Simeon Singer.
The lyrics that the crowd sing between 0:37 and 0:49 are
Ani ma'amin
b'e munah sh'leimah
b'viat ha mashiach,
Ani ma'amin.
mashiach, mashiach, mashiach
where the first three lines mean:
I believe with perfect faith in the coming of the Messiah, and, though he tarry, I will wait daily for his coming.
Source: https://www.zemirotdatabase.org/view_song.php?id=49.
Another version of the song by Mordechai Ben David is here and a recent cover by is here.