Acelakavagga

Vinayapiṭaka · Parivāra · Vol. 8 · Section 335

[335] A bhikkhu engaging in sitting down in private, he alone with a woman (mātugāma) alone, incurs two offences (āpatti): in the act of sitting down, there is an offence of wrong-doing (dukkaṭa); when he has sat down, there is an offence entailing expiation (pācittiya).

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 8 · Section 320 — Ovādavagga