Dhammapada · 12.1

Attānañce piyaṃ jaññā, rakkheyya naṃ surakkhitaṃ;Tiṇṇaṃ aññataraṃ yāmaṃ, paṭijaggeyya paṇḍito.

Attanance piyam janna, rakkheyya nam surakkhitam; Tinnam annataram yamam, patijaggeyya pandito.

If one holds oneself dear, let one guard oneself well. The wise watches in at least one of the three watches of the night.

— Dhammapada 12.1

Source: Pali text from the Khuddaka Nikāya of the Pali Canon (oldest extant Buddhist scripture, compiled c. 3rd century BCE). Public-domain English readings drawn from F. Max Müller's translation in Sacred Books of the East, Vol X (1881) and the Buddhist Publication Society's freely-licensed Acharya Buddharakkhita rendering.