Musannaf Ibn Abi Shaybah 8543 — The eclipse prayer: how many rakahs it

Al-Ala' bin Ziyad said about the lunar eclipse prayer: The imam will recite while standing and bow. When he says 'Sami' Allahu liman hamidah' (Allah hears the one who praises Him), he should look at the moon. If the moon has not become clear, he should recite, then bow, then raise his head. When he says 'Sami' Allahu liman hamidah', he should look at the moon; if it has not become clear, he should recite, then bow, then raise his head. When he says 'Sami' Allahu liman hamidah', he should look at the moon. If it has become clear, he should prostrate, then stand and join another rak'ah to it. If the moon has not become clear, he should not prostrate at all until the moon becomes clear, whenever that may be. Then, if there is an eclipse again after that, he should not pray this prayer.