There is a proposition in palaeoslavistics that the reconstructed prototype of the Izbornik of 1076 is a composition designated as the Kniazheskii Izbornik, which originated from the time of the Bulgarian Tsar Peter (927–969). This article presents an overview of the contents of three manuscripts, which are copies of texts in the so-called Kniazheskii Izbornik: No. 162 from the collection of the Moscow Theological Academy, from the 15th century, Russian origin; No. 189 from the collection of the Hilandar Monastery and which is composed of two parts: Part 1 from the beginning of the 17th century, probably written by a copyist from Moldavia, and Part 2 from 1684, Russian in origin; and No. 280 (333) from the collection of St. Synod of the Romanian Orthodox Church, 15th–16th century, Moldavian in origin. There are suggestions for primary sources of these manuscripts, and the article considers the paths by which texts identical to the Kniazheskii Izbornik found their way into miscellanies in the Late Middle Ages. The three miscellanies under discussion are important witnesses of the paraenetic literature in the earliest period of the Slavia Orthodoxa, which integrated homilies of John Chrysostom, question and answers, interpretations of the Scripture, wise sayings, narration, and apophthegmata from the Paterikon and fragments of the Kniazheskii Izbornik.