Дигха Никая 1:465
SUJATOYasmiṁ, ānanda, samaye tathāgato sabbanimittānaṁ amanasikārā ekaccānaṁ vedanānaṁ nirodhā animittaṁ cetosamādhiṁ upasampajja viharati, phāsutaro, ānanda, tasmiṁ samaye tathāgatassa kāyo hoti.
Sometimes the Realized One, not focusing on any signs, and with the cessation of certain feelings, enters and remains in the signless immersion of the heart. Only then does the Realized One’s body become more comfortable.