My heart is resting, O my God. Anna L. Waring. [The Lord the Portion of his people.] Appeared in the 4th edition of her Hymns and Meditations, 1854, p. 65, in 11 stanzas of 8 lines, and based upon Lam. iii. 24, "The Lord is my Portion, saith my soul; therefore will I hope in Him" (ed. 1871, p. 62). It is also in her Additional Hymns, 1858. Being too long to be used in full, various arrangements of lines and stanzas have been adopted for common use. Most of these begin with the opening line of the hymn. One exception is, "I have a heritage of joy," in the American Unitarian Hymn [<& Tune] Book for Church & Home, Boston, 1868, which begins with stanza iii., line 5.
--John Julian, Dictionary of Hymnology (1907)