Absolutely gorgeous 15th-century binding - not terribly large at ~21 x 13 cm, but, rebacking aside, in splendid condition. Unfair question (doublure not pictured, because it's a dead giveaway): what language is this manuscript in?

"Canonici Ital." is an excellent hint... and do stop to admire this doublure too.

It's @bodleianlibs MS. Canon. Ital. 78, a Florentine copy of Petrarch's Canzoniere and Trionfi, dated to the third quarter of the 15th century.
https://medieval.bodleian.ox.ac.uk/catalog/manuscript_2791

[Digital version (partial) here, with much better (zoomable) images: https://digital.bodleian.ox.ac.uk/objects/a8a334e7-ffc6-4cdc-88f4-8ffa6dacbd56/]

You'll note that the catalogue suggests the manuscript may have been bound in Istanbul by an Ottoman binder, a speculative attribution based on Anthony Hobson's work.

@AoAlio convincingly argued that the binding was more likely the work of a Mamluk binder in her 2012 thesis "Covering the book: bindings of the Mamluk period, 1250-1516 CE." See pp.508-9:

"A manuscript dated to between 1460-70 of Petrarch’s Canzoniere and Trionfi in
the Bodleian Library is Florentine but may have been bound by a Mamluk binder. It has no flap but the Islamic sewing is still discernible
although it has been rebacked." 1/5

"The cover of this Florentine manuscript can be closely compared to the binding of another manuscript prepared for Sultan Qaytbay in two volumes dated 895/1490 of Dimyati’s Mashāri‘ al-ashwāq ilā maṣ āri‘ al-ushshāq." 2/5

"The medallions are filled with fine arabesques repeated in the cusped corner-pieces which contain wide, cup-like palmettes that appear on
several Mamluk covers. The finely tooled knotwork border can also be compared to Mamluk examples." 3/5

"Hobson has given the cover of the Canzoniere
manuscript an Ottoman attribution and cites two examples of bindings for Mehmed II dated 867/1462-3." 4/5

"Segmented borders had, however, been generally abandoned by Ottoman binders by the middle of the 15th century
suggesting that this manuscript was bound in the Mamluk realm." 5/5

[If you haven't read her thesis, which is extensively illustrated and has a v useful appendix, you'll find it here (you should, if bindings of this period interest you):
https://eprints.soas.ac.uk/16626/ ]

Whether you favour identifying this binding as Ottoman or Mamluk, the absence of any provenance in the catalogue earlier than 18th-c Italy leaves the question of this Italian manuscript's 15th-century circulation tantalisingly unanswered.

[And reminds me just how easily I confuse some 15th-century Mamluk and Ottoman bindings at first sight.]