Matthew 15:16

“And Jesus said, etc.] As wondering at, and as being displeased with, and as reproving them for their dulness and ignorance: are ye also yet without understanding? you, my disciples, as well as the Scribes and Pharisees; you, who have been with me so long, who have heard so many discourses from me, who for so long a time have been instructed by me, both in private, and in public; and yet do not understand what is so plain and easy, that has nothing of difficulty in it, but what might easily be accounted for.”

“And Jesus said, Are ye also yet without understanding?--Slowness of spiritual apprehension in His genuine disciples grieves the Saviour: from others He expects no better (Mat 13:11).”

“See also Mark 7:17-23. Then answered Peter, and said unto him, Declare unto us this parable - See the notes at Matthew 13:3. The word “parable” sometimes means a dark or obscure saying, Psalms 78:2. Peter meant, “Explain to us more fully this obscure and novel doctrine.” To us, now, it is plain; to the disciples, just coming out of Judaism, the doctrine of Jesus was obscure. Mark says that the disciples asked him. There is no contradiction. The question was put by Peter in the name of the disciples; or several of them put the question, though Matthew has mentioned only one. An omission is not a contradiction. Matthew 15:16 Are ye also yet without understanding? - Jesus appeals, in explaining…”

“Mat 15:10, Mat 13:51, Mat 16:9, Mat 16:11; Isa 28:9, Isa 28:10; Mar 6:52, Mar 7:18, Mar 8:17, Mar 8:18, Mar 9:32; Luk 9:45; Luk 18:34, Luk 24:45; Heb 5:12 Matthew 15:17”