As I discuss in this answer, Ravana, Kumbhakarna, and Vibhishana were sons of the sage Vishravas and the demoness Kaikeshi. But they weren't Vishravas' first children. Before he met Kaikeshi, Vishravas was married to a woman named Ilavida, and their son was Kubera god of wealth. But the Brahma Vaivarta Purana says this wasn't Kubera's first birth.
According to this excerpt from the Brahma Vaivarta Purana, Kubera was originally born from the body of Krishna. (The Brahma-Vaivarta Purana conceives of Krishna as the supreme god living in Goloka.) But then he was reborn as the son of Vishravas, after a curse by the sage Utathya:
Once Utathya demanded a crore of gold coins from Kubera to pay gurudakshina to his teacher. Kubera in turn behaved with him quite harshly as a result of which Kubera was to be reborn. Thus Kubera was born again of Vishvashrava and the brother Ravana, Kumbhakarna, and Vibhishana who was quite a religious one.
For those who don't know, Uthathya, also known as Uchathya, is the son of the sage Angiras and the brother of Brihaspati guru of the gods. The story he's most known for is that once Brihaspati impregnated Uchathya's wife Mamata. But there was already a child in Mamata's womb, and this unborn child objected to the impregnation. Bribaspati was angered by this and cursed the child to be blind. As a result, Mamata gave birth to two sons, Brihaspati's son Bharadhwaja and Utathya's son Dirghatamas, who was indeed blind. Both grew up to be illustrious sages, as you can see in the Rig Veda Anukramani in my answer here.
In any case, my question is, what other scriptures describe this story of Kubera being burnt to ashes by Utathya and then being reborn? The Brahma Vaivarta Purana is considered to have a lot of interpolations, and the story presented here is centered around Krishna, so I'd like to see whether other scriptures confirm at least the broad outlines of this story.
The only other reference to a disciple of Utathya I know of is in this excerpt from the Skanda Purana, which says that Utathya was the guru of Vishnu's incarnation Mandhata (whom I discuss here). But are there any scriptures which describe Utathya as Kubera's guru?