Meanwhile the people had gathered in thousands, so that they trod upon one another, when Jesus, addressing himself to his disciples, began by saying to them: "Be on your guard against the leaven--that is, the hypocrisy--of the Pharisees.

While all the people were listening, Jesus said to the disciples:

And understand

So Philip ran up, and he heard the Abyssinian reading the Prophet Isaiah. "Do you understand what you are reading?" he asked.

General references

Let him who has ears hear."

Then Jesus speaking to the crowds and to his disciples, said:

And Jesus said: "Let any one who has ears to hear with hear."