The Tipiṭaka in Three Languages

Ekādasakamātikā

Abhidhammapiṭaka · Dhammasaṅgaṇī · Vol. 34 · Section 552

[552] Which is that form (rūpa) that is internal? The eye sense base (cakkhāyatana) … the body sense base (kāyāyatana) — this is that form that is internal. Which is that form that is external? The form sense base (rūpāyatana) … edible nutriment (kabaḷiṅkāra āhāra) — this is that form that is external.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 5 other places