Dasuttarasutta

Suttapiṭaka · Dīghanikāya · Pāthikavagga · Vol. 11 · Section 397

[397] What three dhammas should be directly known (abhiññeyyā)? The three elements (dhātu): the sensual element (kāmadhātu), the form element (rūpadhātu), and the formless element (arūpadhātu). These three dhammas should be directly known.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 11 · Section 386 — Dasuttarasutta