John Gill Commentary John 11:12

"The disciples therefore said unto him, Lord, if he is fallen asleep, he will recover." — John 11:12 (ASV)

Then said his disciples, Lord, if he sleep
Soundly, quietly, and comfortably, and takes rest in it:

he shall do well ;
or "be saved" from the disease; he will be delivered from it; he will recover out of it; it is a sign the distemper is leaving him, and he is growing better, and will be restored to his health again: the Ethiopic version renders it by many words, "he will be well", and "will awake", and "will live". Sound sleep is a sign of health. This they said to, put off their master from going into Judea, fearing the danger he would be exposed unto.