Atthuddhārakaṇda

Abhidhammapiṭaka · Dhammasaṅgaṇī · Vol. 34 · Section 953

[953] Which phenomena (dhammā) are internal (ajjhattika)? The eye sense base (cakkhāyatana) … the mind sense base (manāyatana) — these phenomena are internal. Which phenomena are external (bāhira)? The form sense base (rūpāyatana) … the dhamma sense base (dhammāyatana) — these phenomena are external.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.