Question

"I trust that none will stretch the seams in putting on the coat, for it may do good service to him whom it fits..." What does it mean?

Answer 1

I think it might mean that forcing something to happen is wasting what it is actually meant for.

Answer 2

@HaileyD that is a good way of saying it. Similar to the saying, "if the shoe fits, wear it." If you stretch the seams of a cot, it is too small for you. To "do good service to" is to provide properly for or to take care of or to protect, etc.