Thank-you
MN121 does mention "attends to the singleness based on the perception of earth" which would suggest the Jhana factor, and maybe the origin of the Earth Nimita. but I will point you to
I would argue here that this singleness is not equivalent between the two, as there are other describers, but refers to the jhana factor and the multiplicity of MN137 {Edit=}which does have some support inMN137 wrote:"There is equanimity coming from multiplicity, dependent on multiplicity; and there is equanimity coming from singleness, dependent on singleness.
"And what is equanimity coming from multiplicity, dependent on multiplicity? There is equanimity with regard to forms, equanimity with regard to sounds...smells...tastes...tactile sensations [& ideas: this word appears in one of the recensions]. This is equanimity coming from multiplicity, dependent on multiplicity.
}AN9.42 wrote:"Then there is the case where a monk, with the complete transcending of perceptions of form, with the disappearance of perceptions of resistance, and not heeding perceptions of diversity, [perceiving,] 'Infinite space,' enters & remains in the dimension of the infinitude of space.
MN106 talks about the mind being immeasurable, & well developed. immeasurable always refers to the Brahmaviharas and well developed would refer to the practice of them. This too is able to reach Jhana, but I do not know of an instance where the suttas are explicit here. so although I do not agree that this is an instance I can not show otherwise.
{Edit = although do see footnote 1
Although the initial description does suggest that the hindrances have been overcome which does suggest Jhana itself, but the alternative to the imperturbable (which can refer to the fourth Jhana as some of the inline notes and footnotes mention) of being commited to discernment seams to sugest Vippasana practice which is often Yoked together with Jhana within the sutta}