This is similar to Matthew, chapter 16:8. However, this reprimand is much sharper. Jesus became aware or knew of their discussions (καὶ γνοὺς). He asked them (λέγει αὐτοῖς) why were they worried, talking, or debating (Τί διαλογίζεσθε) about not having any bread (ὅτι ἄρτους οὐκ ἔχετε)? Jesus wanted to know if they still did not perceive (οὔπω νοεῖτε) or understand (οὐδὲ συνίετε) because of their hardened hearts (πεπωρωμένην ἔχετε τὴν καρδίαν ὑμῶν). These disciples were missing the point about Jesus, since he would provide nourishment for them. Instead of calling them men of little faith, as Matthew did, Mark implies that Jesus seemed to indicate that they were stupid with hard hearts.
This is similar to Mark, chapter 8:17, where the reprimand is much sharper. Jesus became aware of their discussions (γνοὺς δὲ ὁ Ἰησοῦς). He reprimanded them by calling them men of little faith (ὀλιγόπιστοι). This word “ὀλιγόπιστοι” was a favorite of Matthew, since 5 of the 6 times it appears in the New Testament literature, Matthew used it. Why were they worried, talking, or debating among themselves (εἶπεν Τί διαλογίζεσθε ἐν ἑαυτοῖς) about not having any bread (ἄρτους οὐκ ἔχετε)? The disciples were missing the point about Jesus, since he would provide nourishment for them.