Blest is the man whose bowels move. I. Watts. [Ps. xli.] This L.M. version of Ps. xlii., stanzas 1-3, which was published in his Psalms of David, &c, 1719, in 4 stanzas of 4 lines, appears in some collections as "Blest is the man whose mercies move;" and in others, "Blest is the man whose heart doth move," the object being to get rid of the, to some, objectionable expression in the first line. These changes are adopted both in Great Britain and in America.
-- John Julian, Dictionary of Hymnology (1907)