Now the disciples had forgotten to take bread - See all this, to Mark 8:21, explained at large on Matthew 16:4-12 (note). In the above chapter, an account is given of the Pharisees, Sadducees, and Herodians.

knew.

Mark 2:8 And immediately when Jesus perceived in his spirit that they so reasoned within themselves, he said to them...

John 2:24,25 But Jesus did not commit himself to them, because he knew all men...

John 16:30 Now are we sure that you know all things, and need not that any man should ask you: by this we believe that you came forth from God.

John 21:17 He said to him the third time, Simon, son of Jonas, love you me? Peter was grieved because he said to him the third time, Love you me?...

Hebrews 4:12,13 For the word of God is quick, and powerful, and sharper than any two edged sword...

Revelation 2:23 And I will kill her children with death; and all the churches shall know that I am he which searches the reins and hearts...

perceive.

Mark 3:5 And when he had looked round about on them with anger, being grieved for the hardness of their hearts, he said to the man...

Mark 6:52 For they considered not the miracle of the loaves: for their heart was hardened.

Mark 16:14 Afterward he appeared to the eleven as they sat at meat, and upbraided them with their unbelief and hardness of heart...

Isaiah 63:17 O LORD, why have you made us to err from your ways, and hardened our heart from your fear? Return for your servants' sake...

Matthew 15:17 Do not you yet understand, that whatever enters in at the mouth goes into the belly, and is cast out into the draught?

Matthew 16:8,9 Which when Jesus perceived, he said to them, O you of little faith, why reason you among yourselves, because you have brought no bread...

Luke 24:25 Then he said to them, O fools, and slow of heart to believe all that the prophets have spoken:

Hebrews 5:11,12 Of whom we have many things to say, and hard to be uttered, seeing you are dull of hearing...

Christ's Cross, and Ours
'And Jesus went out, and His disciples, into the towns of Caesarea Philippi: and by the way He asked His disciples, saying unto them, Whom do men say that I am? 28. And they answered, John the Baptist: but some say, Elias; and others, One of the prophets. 29. And He saith unto them, But whom say ye that I am? And Peter answereth and saith unto Him, Thou art the Christ. 30. And He charged them that they should tell no man of Him. 31. And He began to teach them, that the Son of Man must suffer many …
Alexander Maclaren—Expositions of Holy Scripture

The Final Controversies in Jerusalem
177. The early Christians were greatly interested in the teachings of Jesus and in his deeds, but they thought oftenest of the victory which by his resurrection he won out of seeming defeat. This is proved by the fact that of the first two gospels over one third, of Luke over one fifth, and of the fourth gospel nearly one half are devoted to the story of the passion and resurrection. This preponderance is not strange in view of the shock which the death of Jesus caused his disciples, and the new …
Rush Rhees—The Life of Jesus of Nazareth

Prayer --The All-Important Essence of Earthly Worship
Where the spiritual consciousness is concerned--the department which asks the question and demands the evidence--no evidence is competent or relevant except such as is spiritual. Only that which is above matter and above logic can be heard, because the very question at issue is the existence and personality of a spiritual and supernatural God. Only the Spirit himself beareth witness with our spirit. This must be done in a spiritual or supernatural way, or it cannot be done at all.--C.L. Chilton The …
Edward M. Bounds—The Reality of Prayer