The Arahant (fully Enlightened monk) Who Was Restless About His Friend 🤔

[Dhammanando]

If Thanuttamo’s citation from Mahasi Sayadaw is the one you had in mind, then it’s from the commentary to the Gaṇakamoggallānasutta.

Satisampajaññāya cā ti satisampajaññāhi samaṅgibhāvatthāya. Dve hi khīṇāsavā satatavihārī ca nosatatavihārī ca. Tattha satatavihārī yaṃkiñci kammaṃ katvāpi phalasamāpattiṃ samāpajjituṃ sakkoti, no satatavihārī pana appamattakepi kicce kiccappasuto hutvā phalasamāpattiṃ appetuṃ na sakkoti.

Tatridaṃ vatthu – eko kira khīṇāsavatthero khīṇāsavasāmaṇeraṃ gahetvā araññavāsaṃ gato, tattha mahātherassa senāsanaṃ pattaṃ, sāmaṇerassa na pāpuṇāti, taṃ vitakkento thero ekadivasampi phalasamāpattiṃ appetuṃ nāsakkhi. Sāmaṇero pana temāsaṃ phalasamāpattiratiyā vītināmetvā ‘‘sappāyo, bhante, araññavāso jāto’’ti theraṃ pucchi. Thero ‘‘na jāto, āvuso’’ti āha. Iti yo evarūpo khīṇāsavo, so ime dhamme ādito paṭṭhāya āvajjitvāva samāpajjituṃ sakkhissatīti dassento ‘‘satisampajaññāya cā’’ti āha.