[446] **"Purified in equanimity and mindfulness (upekkhāsatisaṃsuddhaṃ)":** "Equanimity (upekkhā)" is that equanimity in the fourth jhāna — the equanimity, the act of being equanimous, the looking on with equanimity, the serenity of mind (citta), the confidence of mind, the neutrality of the mind. "Mindfulness (sati)" is that mindfulness arisen with reference to the equanimity in the fourth jhāna — the mindfulness, the recollection … right mindfulness; hence "equanimity and mindfulness."
"Purified (saṃsuddhaṃ)": in the fourth jhāna, equanimity and mindfulness are pure, purified, cleansed, unblemished, free from mental defilements (upakkilesa), become malleable, wieldy, steady, attained to imperturbability (āneñja); hence "purified in equanimity and mindfulness."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.