E. Spenser, The Faerie Queene, 1590, reprint. London and New York, 1977, A.C. Hamilton, ed.
Una is the personification of Truth, and she encounters the lion in Book I. canto iii.5. He was about to pounce on her, but repents and instead 'kist her wearie fett'. It was a popular myth that lions protected virgins from this point onwards, and the lion stayed by Una's side protecting her from various perils.