One verse

Srimad Bhagavatam 8.9.26

8.9.26

शिरस्त्वमरतां नीतमजो ग्रहमचीक्लृपत् । यस्तु पर्वणि चन्द्रार्कावभिधावति वैरधी: ॥ २६ ॥

siras tv amaratam nitam ajo graham aciklpat yas tu parvani candrarkav abhidhavati vaira-dhih

sirah
the head
tu
of course
amaratam
immortality
nitam
having obtained
ajah
Lord Brahma
graham
as one of the planes
aciklpat
recognized
yah
the same Rahu
tu
indeed
parvani
during the periods of the full moon and dark moon
candra-arkau
both the moon and the sun
abhidhavati
chases
vaira-dhih
because of animosity.

Rahu’s head, however, having been touched by the nectar, became immortal. Thus Lord Brahma accepted Rahu’s head as one of the planes. Since Rahu is an eternal enemy of the moon and the sun, he always tries to attack them on the nights of the full moon and the dark moon.