Concept:
The quoted verse is a foundational ethical teaching in Buddhism, emphasizing the causal relationship between one's conduct (Kamma) and their state of well-being (Sukha). The verse translates to: "One should practice the Dhamma well; one should not practice it badly. The righteous liver sleeps happily in this world and in the next." Such pithy, rhythmic, and morally instructive verses are characteristic of the *Dhammapada*.
Step 1: Identifying the verse within the Dhammapada.
This specific verse is found in the Dhammapada, specifically in the Lokavagga (Chapter on the World), as verse number 168 (or 169 depending on the edition). The *Dhammapada* is designed to be a handbook of Buddhist ethics, making it the most likely source for such a general exhortation to "live righteously."
Step 2: Evaluating alternative Pali texts.
• Therīgāthā: Contains verses of the elder nuns; while poetic, they are usually personal accounts of liberation rather than general moral commands.
• Vinayapiṭaka: Primarily contains the rules of monastic discipline; it is prose-heavy and focused on legalistic structures.
• Udāna: Contains "inspired utterances" usually followed by a prose story explaining the context. While it contains verses, this specific "Dhammacārī" verse is the hallmark of the *Dhammapada*.