John Gill Commentary Matthew 15:29

"And Jesus departed thence, and came nigh unto the sea of Galilee; and he went up into the mountain, and sat there." — Matthew 15:29 (ASV)

And Jesus departed from thence
From the coasts of Tyre and Sidon, where he would have been private and retired; but being discovered, and knowing that the fame of this last miracle would make him more public in those parts, he removed, and passed through the midst of the coast of Decapolis, as Mark says, "and came nigh unto the sea of Galilee": the same with the sea of Tiberias. (John 6:1) (21:1) , that is, he came to those parts of Galilee, which lay near the sea side,

and went into a mountain
which was very usual with him, either for solitude, or for prayer, and sometimes, for better conveniency, to preach to the people:

and sat down there
to take some rest, being weary with his journey, and as waiting for the multitude to come to him, both for instruction and healing.