Many people wrongly interpret this as Jesus (as the Son of God) saying it to the Father. However, the scriptures point otherwise. When Jesus said He was hungry, thirsty or tired, we very well know that it is His human nature. Similarly, here in this context, it is the human nature of Jesus praying to the Spirit of God.
And those trinitarians who argue that this is “God the Son” praying to “God the Father”, they must first realize that the term “God the Son” or “the eternal Son” is unbiblical. The Bible only uses the term “Son of God”. And as far the term “eternal Son” is concerned, the Bible does not advocate any such heresy. The Bible clearly says that the office of Christ / Sonship has a beginning and an end.
Now, coming to the main argument, if one person of the trinity is saying that sentence to another person of the trinity, then it implies that there is a difference of will between their so-called trinity: Which further implies that there is no perfect harmony between the trinity as they suppose, and collapses their belief.