Visuddhimagga VIII-4

168. Taṃ bhāvetukāmena rahogatena paṭisallīnena ‘‘maraṇaṃ bhavissati, jīvitindriyaṃ upacchijjissatī’’ti vā, ‘‘maraṇaṃ maraṇa’’nti vā yoniso manasikāro pavattetabbo.

（念死的修法之一）欲修念死的人，独居静处，当起「死将来临」，「命根将断」，或「死，死」的如理作意。

[Development]

Ñ(VIII,4): One who wants to develop this should go into solitary retreat and exercise attention wisely in this way: 'Death will take place; the life faculty will be interrupted', or 'Death, death'.