From The Gospel of Mark, by Mary Healy, commenting on Mark 7:31-37
When Jesus arrives in the Decapolis he meets with a very different reception than on his first visit, when the people begged him to leave (5:17). Perhaps his way has been prepared by an unlikely evangelist: the liberated demoniac, who broadcast to the whole region what Jesus had done for him (5:20).
Now the inhabitants recognize Jesus as a worker of mighty deeds who has compassion on the afflicted. So they bring to him a deaf man, begging him to lay his hand on him (as in 5:23). The rare word for speech impediment (mogilalos) appears only once elsewhere in Scripture, in the Greek translation of a prophecy of Isaiah: “Then will the eyes of the blind be opened, the ears of the deaf be cleared; Then will the lame leap like a stag, then the tongue of the dumb will sing” (Isa 35:5–6).
This exultant promise refers to the joyful return home of the Jews after their exile in Babylon, but Mark is hinting that the Gentiles too are now heirs to these blessings. Previously deaf to God and mute concerning his saving deeds, now, in response to his mighty works of healing, they are able to hear his voice and sing his praises.
Many of Jesus’ healings take place in full public view (see 3:3), but here, in contrast, he takes the man off by himself (see also 8:23). This detail suggests that Jesus intuitively understands the unique needs of each person. For some people it is important to have a private encounter, away from the stares of the crowd, so that Jesus can minister to their needs one-on-one. Jesus performs the healing in no less than seven steps, as if speaking in sign language so the deaf man can follow what he is doing.