The following is an excerpt from
The MacArthur New Testament Commentary on John 20.
Jesus said to her, “Mary!” She turned and said to Him in Hebrew, “Rabboni!” (which means, Teacher). Jesus said to her, “Stop clinging to Me, for I have not yet ascended to the Father; but go to My brethren and say to them, ‘I ascend to My Father and your Father, and My God and your God.’ ” Mary Magdalene came, announcing to the disciples, “I have seen the Lord,” and that He had said these things to her. (John 20:16–18)
With a single word, Jesus opened Mary’s eyes. He merely spoke her name (cf. 10:3–4, 27), “Mary!” and in a flash all of her doubt, confusion, and sorrow vanished. Recognizing Jesus in that moment, she turned and said to Him in Hebrew, “Rabboni!” (which means, Teacher). Rabboni is a strengthened form of “Rabbi,” and was used as a title to express great honor and supreme reverence (cf. Mark 10:51). Overcome with a profound mix of joy and relief, Mary fell at His feet. Like the other women had done (Matt. 28:9), she clung to Jesus, prompting Him to say to her, Stop clinging to Me, for I have not yet ascended to the Father. Having found Him again beyond her wildest hopes, she did not want to lose Him. Her physical grasp symbolized her desire to secure His presence permanently. But He would be physically present for only a brief time, forty days (Acts 1:3), after which He would ascend to the Father. How much knowledge she had of what Jesus had promised in the upper room is not known. But perhaps she had been told by the apostles that He said He was going to the Father to send the Holy Spirit (14:16–18; 16:7), so He said nothing about that, only that He could not stay, but must ascend.