a.1982, Bobbi Morris (?), quoted in Steven M. Tipton, Getting Saved from the Sixties: Moral Meaning in Conversion and Cultural Change, University of California Press (1982), ISBN9780520038684, page 52:
Therefore I call unto thee, repent before me. Humble thyselves. Humble thyselves before me that I may forgive thy sin.
1993, Edward James Blakely and Sumner M. Sharp, Planners, Heal Thyselves: Planning Education, Educators, and Practitioners in the Next Century, University of California, Berkeley, Institute of Urban and Regional Planning.
1999, Tom Hirschfeld, Business Dad: How Good Businessmen Can Make Great Fathers (and Vice Versa), Little, Brown and Company (2000), ISBN978-0-316-21915-0, page 62:
When the pronoun thou was in common use, it was specifically singular (and often specifically informal). However, in current use, where thou survives as an archaism, this distinction is not actively maintained, and many speakers treat thou simply as an archaic synonym of you, enabling thyselves to be coined as a pseudo-archaic synonym of yourselves.