In the four scriptures we read (2 Cor. 12:7; Num 33:55; Joshua 23:13, Judges 2:3) we see that the use of the word ‘thorn in the flesh’, ‘thorn in your eyes’ and ‘thorn in your sides’ across the Bible is used by the writers as an expression in the same way today we would say someone was being a ‘pain in the side’ or other expressions like someone was going to ‘face the music’ or ‘get their act together.’ In interpreting these expressions you would take the meaning of whole phrase as one rather than focusing on each individual word.
Jesus challenged them in what they described as a gift (Corban) to God in Matthew 11:5. A Corban represented an offering an made to God, withdrawn from its originally intended use, and no longer available for persons, not even for those in need. They said one could avoid honouring their father and mother (providing financial support to them) by offering a Corban. Once something was designated a Corban no one else could benefit from it other than the person who designated it. In doing this they were violating the commandment of God making it ineffective.