Navasīvathikapabbaṁ This heading is only found in ChS (though there given as -sivathika-). The titles given below, starting with Paṭhamaṁ Sīvathikaṁ have been extracted from the end-titles in BJT.01
The Section about the Nine Charnel Grounds

Paṭhamaṁ Sīvathikaṁ
The First Charnel Ground

 

Puna ca paraṁ, bhikkhave, bhikkhu seyyathā pi
Moreover, monks, it's as if a monk

passeyya sarīraṁ sīvathikāya A charnel ground is a place where bodies were left on the ground, sometimes elevated ground, to be devoured by animals or birds. PED suggests the word may be related to Śivālaya, but Śiva was not known by that name in Lord Buddha's time, so the explanation is problematic.02 chaḍḍitaṁ,
might see a body thrown into a charnel ground,

ekāhamataṁ vā dvīhamataṁ vā tīhamataṁ vā,
dead for one day, or dead for two days, or dead for three days,

uddhumātakaṁ vinīlakaṁ More exactly, vinīlaka means blue-coloured.03 vipubbakajātaṁ.
bloated, discoloured, having become quite rotten.

So imam-eva kāyaṁ upasaṁharati: In most countries these days there are no charnel grounds and it is not so easy to find abandoned bodies to do this practice, so monks in Buddhist countries often visit morgues or dissection rooms in hospitals. If actual dead bodies are not available, it is always possible to use one's imagination. The point of the exercise is not morbidity, but insight, so a degree of spiritual maturity and stability should be established before attempting the practice, which should preferably be done under the guidance of an experienced teacher. Monks in the time of the Buddha who did this practice without guidance started killing themselves (see the opening to Pārājika III in the Vinaya Suttavibhaṅga).04
He then compares it with his very own body (thinking):

“Ayam-pi kho kāyo evaṁdhammo evaṁbhāvī -bhāvī here is the possessive suffix, not the participle suffix, as can be seen from its nominal nature and independence from a finite verb.05 etaṁ anatīto” ti.
“This body also has such a nature, has such a constitution, has not gone beyond this.”

* * *

Iti ajjhattaṁ vā kāye kāyānupassī viharati,
Thus he dwells contemplating (the nature of) the body in the body in regard to himself,

bahiddhā vā kāye kāyānupassī viharati,
or he dwells contemplating (the nature of) the body in the body in regard to others,

ajjhattabahiddhā vā kāye kāyānupassī viharati,
or he dwells contemplating (the nature of) the body in the body in regard to himself and in regard to others,

samudayadhammānupassī vā kāyasmiṁ viharati,
or he dwells contemplating the nature of origination in the body,

vayadhammānupassī vā kāyasmiṁ viharati,
or he dwells contemplating the nature of dissolution in the body,

samudayavayadhammānupassī vā kāyasmiṁ viharati,
or he dwells contemplating the nature of origination and dissolution in the body,

“atthi kāyo” ti vā panassa sati paccupaṭṭhitā hoti
or else mindfulness that “there is a body” is established in him

yāvad-eva ñāṇamattāya patissatimattāya,
just as far as (is necessary for) a full measure of knowledge and a full measure of mindfulness,

anissito ca viharati, na ca kiñci loke upādiyati.
and he dwells independent, and without being attached to anything in the world.

Evam-pi kho, bhikkhave, bhikkhu kāye kāyānupassī viharati.
In this way, monks, a monk dwells contemplating (the nature of) the body in the body.

(Paṭhamaṁ Sīvathikaṁ)
(The First Charnel Ground)