The Tipiṭaka in Three Languages

Suññatavāra

Abhidhammapiṭaka · Dhammasaṅgaṇī · Vol. 34 · Section 408

[408] What, on that occasion, is one-pointedness of mind (cittassa ekaggatā)? That stability (ṭhiti) of mind (citta) which there is on that occasion — this, on that occasion, is one-pointedness of mind.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 5 other places