What enters the mind of an idle Buddha? What enters the mind of a Buddha when left idle? Suppose a Buddha were confined to a hospital bed or prison cell. One cannot remain within the conditioned states of jhana indefinitely. If one is unconditionally content, even in states of pain, it would seem there is no need to reflect or contemplate anything. Can you cite specific examples from the Buddha's life?
From parinibbana suttha 


  
    16: The Gracious One’s Sickness
  
  
  Then the Gracious One, after living near Ambapālī’s Wood for as long
  as he liked, addressed venerable Ānanda, saying: “Come Ānanda let us
  approach the little village of Beluva.”
  
  “Very well, reverend Sir,” venerable Ānanda replied to the Gracious
  One. Then the Gracious One together with a great Community of monks
  arrived at the little village of Beluva. There the Gracious One lived
  near the little village of Beluva.
  
  There the Gracious One addressed the monks, saying: “Go, monks, and
  undertake the Rains Retreat in the vicinity of Vesālī living like
  friends, like companions, like comrades, and I will spend the Rains
  Retreat right here at the little village of Beluva.”
  
  “Very well, reverend Sir,” and those monks, after replying to the
  Gracious One, undertook the Rains Retreat in the vicinity of Vesālī
  living like friends, like companions, like comrades. But the Gracious
  One spent the Rains Retreat right there at the little village of
  Beluva.
  
  Then while dwelling for the Rains Retreat, a heavy affliction arose
  for the Gracious One, and continued with strong and death-like
  feelings. There the Gracious One dwelt mindfully, with full awareness,
  and without being troubled. Then this occurred to the Gracious One:
  “It is not suitable that I, without having addressed my attendants,
  without having given notice to the Community of monks, should attain
  Final Emancipation. Having energetically dismissed this affliction, I
  could live on after determining the lifespan.”
  
  Then the Gracious One having energetically dismissed that affliction
  lived on after determining the lifespan. Then the Gracious One’s
  affliction abated. Then, the Gracious One, having risen from that
  sickness, not long after rising, departed from the Sick Room and sat
  down on the prepared seat in front of that Room.
  
  Then venerable Ānanda approached the Gracious One, and after
  approaching and worshipping the Gracious One, he sat down on one side.
  While sitting on one side venerable Ānanda said this to the Gracious
  One:
  
  “I have seen, reverend Sir, the Gracious One comfortable, I have seen,
  reverend Sir, the Gracious One bearing up while sick, and my body,
  reverend Sir, became faint as it were, and although I could not see
  straight, and things were not clear, it appeared to me, reverend Sir,
  that the Gracious One was sick, but it was some small comfort that the
  Gracious One would not attain Final Emancipation until the Gracious
  One had spoken regarding the Community of monks.”
  
  “But what, Ānanda, does the Community of monks expect of me? The
  Teaching has been taught by me, Ānanda, without having made a
  distinction between esoteric and exoteric, for the Realised One there
  is nothing, Ānanda, of a closed teacher’s fist in regard to the
  Teaching.
  
  To whoever, Ānanda, this thought occurs: ‘I will lead the Community of
  monks’ or ‘I am the instructer of the Community of monks’ let him
  speak, Ānanda, regarding the Community of monks. But to the Realised
  One, Ānanda, this thought does not occur: ‘I will lead the Community
  of monks’ or ‘I am the instructor of the Community of monks’. Then
  why, Ānanda, should the Realised One speak regarding the Community of
  monks?
  
  I, Ānanda, at present, am old, elderly, of great age, far gone,
  advanced in years, I am eighty years old. It is like, Ānanda, an old
  cart, which only keeps going when shored up with bamboo, just so,
  Ānanda, I think the Realised One’s body only keeps going when shored
  up with bamboo.
  
  When the Realised One doesn’t pay attention, Ānanda, to any of the
  signs, when all feelings have ceased, he lives having established the
  signless mind-concentration, and at that time, Ānanda, the Realised
  One’s body is most comfortable.
  
  Therefore, Ānanda, live with yourself as an island, yourself as a
  refuge, with no other refuge, with the Teaching as an island, the
  Teaching as a refuge, with no other refuge. And how, Ānanda, does a
  monk live with himself as an island, himself as a refuge, with no
  other refuge, with the Teaching as an island, the Teaching as a
  refuge, with no other refuge?
  
  Here, Ānanda, a monk dwells contemplating the nature of the body in
  the body, ardent, fully aware, and mindful, after removing avarice and
  sorrow regarding the world; he dwells contemplating the nature of
  feelings in feelings, ardent, fully aware, and mindful, after removing
  avarice and sorrow regarding the world; he dwells contemplating the
  nature of the mind in the mind, ardent, fully aware, and mindful,
  after removing avarice and sorrow regarding the world; he dwells
  contemplating the nature of things in various things, ardent, fully
  aware, and mindful, after removing avarice and sorrow regarding the
  world.
  
  Thus, Ānanda, a monk lives with himself as an island, himself as a
  refuge, with no other refuge, with the Teaching as an island, the
  Teaching as a refuge, with no other refuge. For whoever, Ānanda,
  whether at present or after my passing, lives with himself as an
  island, himself as a refuge, with no other refuge, with the Teaching
  as an island, the Teaching as a refuge, with no other refuge, those
  monks of mine, Ānanda, will go from darkness to the highest—whoever
  likes the training.”
  
  The Second Chapter for Recital is Finished.