What literary device was used when Romeo states, "I fear too early for my mind misgives..."?
Let's look at the full quote that you are referring to first, which occurs in Act One, Scene Four of Romeo and Juliet:
I fear too early, for my mind misgives
Some consequence yet hanging in the stars
Shall bitterly begin his fearful date
With this night’s revels, and expire the term
Of a despisèd life closed in my breast
By some vile forfeit of untimely death.
But he that hath the steerage of my course,
Direct my sail. On, lusty gentlemen.
First, this passage is an example of foreshadowing. Romeo is telling Benvolio that he fears that something bad will happen at the ball later that night which may eventually result in his death. This premonition is absolutely true: Romeo will meet his future wife, Juliet, the woman from the rivaling Capulet family who will later committee suicide with Romeo in the crypt.
The literary device that is used in Romeo's quote, "I fear, too early; for my mind misgives/ Some consequence yet hanging in the stars," (Act I, scene v, l. 106-107) is two fold.
"My mind misgives" is personification because it is giving the mind capability to perform a human action. It is also foreshadowing, because Romeo is hinting at a future occurrence that has yet to be discovered in the "some consequence yet hanging in the starts" portion of the line.