Mark 1:30
But Simon's wife's mother lay sick of a fever, and anon they tell him of her.
But Simon's wife's mother lay sick of a fever,.... "A great fever", Luke says, Luke 4:38; a very violent one, which threatened with death, and must be very dangerous to an old person;
See Gill on "Matthew 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 sat awhile, and rested himself after his fatigue in preaching; they acquainted him with her case, and beseeched him to look upon her, and restore her: this was done, either by Simon and Andrew, or by some others of their friends that were in the house; who having either seen, or heard of his dispossessing the unclean spirit, might rightly conclude he had power to remove a fever.