Friar Lawrence uses personification when he describes the morning as having eyes.
Personification is describing something non-human as you would a human. When Friar Lawrence is picking flowers, which he uses for different potions. He describes the morning as smiling at night.
The grey-ey'd morn smiles on the frowning night,
Check'ring the Eastern clouds with streaks of light (Act 2, Scene 3)
This is personification because the morning is smiling, which only a human can do. By using this figurative language, Friar Lawrence is establishing the setting and painting a picture worthy of flowers and love. Romeo is about to come in and tell him that he is love with Juliet.
In Act II Scene 3, Romeo comes to Friar Lawrence to ask that he marry Romeo and Juliet – the good Friar chides Romeo for having so readily abandoned Rosaline for another, and agrees to wed them in hopes that the act will resolve the feud between their families. Before all this takes place, however, we have Friar Lawrence alone, waxing poetic as he goes to pick weeds and flowers early in the morning, talking to himself about the day and the earth, and personifying everything he can set his eyes on.
Personification is the attribution of human traits to non-human things, and we have plenty of examples from the Friar’s first monologue, beginning, indeed, with the first line: “The grey-eyed morn smiles on the frowning night.” Here we have a dawn with a humans’ grey eyes, smiling like a human does on the darkness it replaces – the night, which is frowning as a human does. An emotionally positive day, and an emotionally negative night. A few lines down the sun is given a “burning eye,” and a few lines after this the Friar speaks of Mother Nature and all of us her children, a vast sweep of all the flora and fauna who feed off the earth – the concept of “Mother Nature” is a common personification, attributing all the nurturing characteristics of a mother to the world around us – a world from which we are nourished, yes, but a world as well that is in reality indifferent to and unaware of our existence.
Further on in the monologue we hear the Friar speaking of a plant, which has a sweet, invigorating smell and yet is poisonous if eaten. These two aspects of the plant's nature he describes as “Two such opposed kings,” personifying the split nature of the plant as two rulers of delight and of misery.
The Friar uses more personification with the following lines:
And flecked darkness like a drunkard reels (II.iii.3)
As morning approaches and the night gives way to daylight, the last fragments ("flecked") of darkness dissipate "like a drunkard." This is a simile in the function of personification. The darkness dissipates here and there, awkwardly - like a drunk person stumbling away.
The Friar continues, personifying the sun - the sun will soon use his (the sun's) "burning eye" to "cheer" the new day.
The Friar uses more examples of personification in his dialogue with Romeo. For instance, the Friar notes to Romeo that "Care keeps his watch in every old man's eye," (II.iii.36). This is a stretch given that "care" is manifested in a person's thoughts or behaviors. But since the human quality is attributed to something non-human (that of abstract "care"), it is a kind of personification.