Who coined "the eye of heaven"?

Solution 1:

OED, Third Edition, provides textual evidence for the concept, expressed variously, from J. Trevisa's translation, composed sometime before 1398, of De Proprietatibus Rerum (On the properties of things), by Bartholomaeus Anglicus.

Sense 11a of 'eye' (entry updated June 2014):

Chiefly poetic and in literary contexts. The sun (also heaven) as the source of light, conceived as an eye or as possessing eyes.
_{Similarly eye of day (also eye of heaven, eye of the world, etc.); eyes of heaven: the stars, esp. seen in the night sky; eye of night: the moon.}

J. Trevisa's translation:

Þe sonne is þe yȝe of þe worlde. [The sun is the eye of the world.]

Conflation of heaven and the sun in OED's derived sense, "as the source of light, conceived as an eye or as possessing eyes", may embellish the particular cases, but OED draws what could be considered an earlier attestation more closely matching the phrasing of interest from Chaucer's Troilus & Criseyde.

The quotation from Chaucer, although probably not evidenced in print until sometime before 1498, was probably composed around 1385:

The dayes honour and the heuenes eye, The nyghtes fo al this clepe I the sonne. [The day's honor and the heaven's eye, the night's foe: all these I call the sun.]

The phrasing of the concept of the sun as an eye, specifically "heaven's eye" or "eye of heaven", likely depends more on metrical or narrative exigency than any putative differentiation of sense.