The manuscript

Description: William Henry Black, A Descriptive, Analytical, and Critical Catalogue of the Manuscripts bequeathed unto the University of Oxford by Elias Ashmole, Esq. (Oxford: Oxford University Press, 1845), cols. 260-76.

Ashmole 360 includes eight MSS bound together; the seventh MS (fols. 138r-150v) is of parchment, with a page size of approximately 156 x 125 cm., and is written in various small hands, in smaller Gothic book hand (including this lyric) and cursive script. The appearance of the MS is functional rather than decorative, with some initials and headings in red. Black dates it to the 13th century. 
Most of its content is in Latin, apart from this English lyric, which is preceded by  extracts from Jerome, Augustine, Bernard of Clairvaux, Ambrose, John Chrysostom, Gregory the Great, and the Glossa Ordinaria. Below the poem, in a different hand, is written O bone Iesu; this is a cross-reference (linked by a concluding mark to a mark in the margin next to the actual quotation) to a passage earlier on the page attributed to Bernard, O bone Iesu, quam dulciter cum hominibus...peniteat his diebus, on a broadly similar theme, that the sufferings of Christ on the cross are so great that they should inspire everyone to reform and repentance.

(note: the Bodleian Library does not allow reproductions of its MSS to be published on unpassworded websites)