The Stage is Yours.

[Mystic]

From which verse is that exactly?

It's probably there, but again, the "we" does not mean that it is referring to God only. There are several verses that say "we" created this and that "we" have preserved the Quran and similar things, but all of those verses are in reference to God along with the angels plus the unseen creatures, hence the plural "we."

It's in Suratal Anbiya when it takes about Ibrahim, Isaac, and Yaqoub being Imams/leaders whom guide by God's Command.

"us did they serve" can be a translation.

Anyways, I don't know why you don't see it as plural majesty. That it's just to emphasize on God's Grandeur.