John 11:12

Verse 12. If he sleep, he shall do well. Sleep was regarded by the Jews, in sickness, as a favourable symptom; hence it was said among them, "Sleep in sickness is a sign of recovery, because it shows that the violence of the disease has abated" (Lightfoot.) This seems to have been the meaning of the disciples. They intimated that if had this symptom, there was no need of his going into Judea to restore him.

Albert Barnes, 1834 · public domain

Verse 12 If he sleep, he shall do well - That is, if he sleep only, etc. Though the word sleep frequently meant death, (see Act 7:60; 1Cor 11:30; 1Cor 15:18, 1Cor 15:20), yet, as it was an ambiguous term, the disciples appear here to have mistaken its meaning. Because, in certain acute disorders, the composing the patient to rest was a favorable sign; therefore the words, If he sleep, he shall do well, or recover, became a proverbial forth of speech among the Jews. In most diseases, sleep is a very favorable prognostic: hence that saying of Menander: - Ὑπνος δε πασης εϚιν ὑγιεια νοσου. Sleep is a remedy for every disease. See Grotius here. The meaning of the disciples seems to have been this: There can be no need for thee to go into Judea to awake our friend Lazarus; he will awake time enough, and his very sleep is a presage of his recovery: therefore do not hazard thy life by going.

Adam Clarke, 1831 · public domain