As you can see in the Anukramani I provided in my answer here, the sage who heard most of the hymns in the Fourth Mandala of the Rig Veda was the sage Vamadeva, a descendantson of the sage Gotama (hence Gautama). Two of the hymns of this Mandala deal mainly with Garuda's theft of the Soma/Amrita (nectar of immortality) from Devaloka. But the beginning of these hymns are considered by the Upanishads to be of profound significance. Here is how Hymn 26 of the Fourth Mandala begins: