Simon’s mother-in-law was sick in bed with a fever, and they promptly told Jesus about her.
In these verses, we have, I. A particular account of one miracle that Christ wrought, in the cure of Peter's wife's mother, who was ill of a fever. This passage we had before, in Matthew. Observe, 1. When Christ had done that which spread his fame throughout all parts, he did not then sit still, as some think that they may lie in bed when their name is up.
Commenting on Mark 1:29-39
But Simon's wife's mother lay sick of a fever,.... "A great fever", Luke says, Luk 4:38; a very violent one, which threatened with death, and must be very dangerous to an old person; See Gill on Mat 8:14, And anon they tell him or her; for it seems, that not as soon as he came into the house, but some time after, when he had...
But Simon's wife's mother lay sick of a fever--Luke, as was natural in "the beloved physician" (Col 4:14), describes it professionally; calling it a "great fever," and thus distinguishing it from that lighter kind which the Greek physicians were wont to call "small fevers," as GALEN, quoted by WETSTEIN, tells us. and anon--immediately.