They speak in reaction to Jesus’ word that all things are possible with God: their own action shows that God can make it happen in the life of a human being (leaving everything and following Jesus). To this statement, however, the question is also connected whether they now will indeed partake in the kingdom of God and life eternal: is not that which is impossible for others their future? With so many words this is stated in Matthew 19:27.1
26 And they were exceedingly astonished, and said to him, “Then who can be saved?”