On the Oral Fixation tour, Shakira started the show singing a couple of lines in Arabic. This snippet is only listed as "intro" in the DVD, and to my eternal shame I must admit I never investigated what these lines were.
On the new tour, the same lines emerged in the middle of the show and a setlist I found on the web names the song as A'tini al-Nay.
Which, it turns out, is a poem by Gibran Khalil Gibran, sung by Fairuz:
And in this interview, Shakira explains how A´tini al-Nay was one of the first songs she performed as a young child, and that people called her the "little Fairuz," and she sings the first two lines again but then says she can't remember the rest of the lyrics.
And here's the version at the beginning of the Oral Fixation concerts, which then blends into Estoy aqui.
I'd love to see her doing a complete cover version of the song, actually. Can we have that on the next album, please?