2018 ...To date there's no evidence that Samuel Adams said this.

Considered a misquote ....
"It is always dangerous to the liberties of the people to have an army stationed among them, over which they have no control" .... Samuel Adams 1775
The Writings of Samuel Adams Vol. III page 230

The Militia is composed of free Citizens. There is therefore no danger of their making use of their Power to the destruction of their own Rights, or suffering others to invade them. Samuel Adams 1776
The Writings of Samuel Adams Vol. III page 251

This quote is correct .... The Writings of Samuel Adams Vol III page 263

This quote is a misquote.
The real quote is ...... A standing Army, however necessary it may be at some times, is always dangerous to the Liberties of the People. Samuel Adams 1776
The Writings of Samuel Adams Vol III page 250

This phrase is NOT found in any Samuel Adams writings and at this time is considered a misquote.