Visuddhimagga XII-88

Evaṃ gantukāmena pana ākāsakasiṇaṃ samāpajjitvā vuṭṭhāya kuṭṭaṃ vā pākāraṃ vā sinerucakkavāḷesupi aññataraṃ pabbataṃ vā āvajjitvā kataparikammena ākāso hotūti adhiṭṭhātabbo.

欲这样无碍而行者，入虚空遍定而出定已，念壁或墙或须弥及轮围等的任何山而遍作（准备），当决意「成虚空」，

Ñ(XII,88): One who wants to go in this way should attain the space-kasiṇa [jhāna] and emerge, and then do the preliminary work by adverting to the wall or the enclosure or some such mountain as Sineru or the World-sphere Mountains, and he should resolve, 'Let there be space'.

Ākāsoyeva hoti.

便成虚空。

Ñ: It becomes space only;

Adho otaritukāmassa, uddhaṃ vā ārohitukāmassa susiro hoti, vinivijjhitvā gantukāmassa chiddo.

欲下降或欲上升者便有坑，欲穿透而行者便有洞。

Ñ: it becomes hollow for him if he wants to go down or up; it becomes cleft for him if he wants to penetrate it.

So tattha asajjamāno gacchati.

他便可从那里无碍而行。

Ñ: He goes through it unhindered.