Father, if Thou my Father art. C. Wesley. [Prayer for the Witness of the Spirit.] Published in Hymns and Sacred Poems, 1740, p. 131, in 6 stanzas of 6 lines,and headed, "Groaning for the Spirit of Adoption" (Poetical Works, 1868-72, vol. i. p. 307). In the Wesleyan Hymn Book, 1780, No. 365, stanzas ii.-vi. were given as "I want the Spirit of power within." This form of the hymn has been repeated in several collections in Great Britain, and America.
--John Julian, Dictionary of Hymnology (1907)