Missionaries are tempted to push their field as the only place in the world. While I am glad that they are so excited about the place God has called them we must all remember that the entire world must have the gospel preached to it!

Check out what Adoniram Judson said:

But while Mr. Judson felt that his appropriate field was Burmah, and nothing but Burmah, he gave to this field no peculiar preeminence. The whole heathen world was always in his view.

He was ever suggesting to the board new fields of labor, and he was constantly bringing before the mercy seat, in his most retired hours of devotion, particular nations who had not yet attracted the attention of the friends of missions. Thus, at Maulmain, he was always urging his brethren, and specially those whom he most highly esteemed, and whose society he most enjoyed, to establish new missions in neighboring unevangelized countries.

In no case, however, did he propose any labor to them which he was not willing to undertake himself. He desired that every one of them, as far as possible, should be a new centre of gospel light, and he wished such centres to be multiplied as widely as possible.
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A memoir of the life and labors of the Rev. Adoniram Judson (Francis Wayland)