There are several pages out there claiming a legend of Rāvaṇa planning to build a staircase in order to get to heaven (or, the region of the moon) without performing Vedic rituals. All of the sources I could find however, can be traced back to Prabhupāda
For exmple, a talk by Prabhupāda given in 1972.
“Why you are undergoing so much severe austerities to go to heaven? I shall make a staircase, and you go directly, without having performed any austerities.”
And from Prabhupāda’s commentary on the Bhāgavata-purāna :
“Rāvaṇa was one of them, and he wanted to deport ordinary men to the planet of Indra (heaven) by material means without consideration of the necessary qualifications. He wanted a staircase to be built up directly reaching the heavenly planet so that people might not be required to undergo the routine of pious work necessary to enter that planet. He also wanted to perform other acts against the established rule of the Lord.”
Are there any older extant sources confirming this legend, or did he use sources currently unavailable to us?