Visuddhimagga X-6

So tattha evaṃ ādīnavaṃ disvā nikantiṃ pariyādāya ākāsānañcāyatanaṃ santato anantato manasikaritvā cakkavāḷapariyantaṃ vā yattakaṃ icchati tattakaṃ vā kasiṇaṃ pattharitvā tena phuṭṭhokāsaṃ ‘‘ākāso ākāso’’ti vā, ‘‘ananto ākāso’’ti vā manasikaronto ugghāṭeti kasiṇaṃ.

他看见这样的过患之后，并盼望除去它，即于空无边处的寂静无边而作意，扩大他的遍至于轮围（世界）的范围或者遂其所欲的远大，以那（扩大了的）遍所触的空间而「虚空！虚空！」或「虚空无边」的这样作意，而除去那遍。

Ñ(X,6): When he has seen the danger in that [fine-material fourth jhāna] in this way and has ended his attachment to it, he gives his attention to the base consisting of boundless space as peaceful. Then, when he has spread out the kasiṇa to the limit of the world-sphere, or as far as he likes, he removes the kasiṇa [materiality] by giving his attention to the space touched by it, [regarding that] as 'space' or 'boundless space'.