John 11:11-16 NIV

11 After he had said this, he went on to tell them, "Our friend1 Lazarus has fallen asleep;2 but I am going there to wake him up."

References for John 11:11

12 His disciples replied, "Lord, if he sleeps, he will get better."
13 Jesus had been speaking of his death, but his disciples thought he meant natural sleep.3

References for John 11:13

14 So then he told them plainly, "Lazarus is dead,
15 and for your sake I am glad I was not there, so that you may believe. But let us go to him."
16 Then Thomas4 (called Didymus) said to the rest of the disciples, "Let us also go, that we may die with him."

References for John 11:16