"But if they become arrogant"—meaning the polytheists, regarding prostration to Allah—"then those who are with your Lord"—meaning the angels—"glorify Him by night and day, and they do not tire," meaning: they do not grow weary.
Mujahid said: I asked Ibn Abbas about the prostration in [Surat] Ha Mim, and he said: Perform the prostration at the latter of the two verses. Ibn Abbas said: And there is no prostration in the Mufassal [section of the Quran].
Tafsir of Surat Fussilat from verse 39 to verse 42.